[SierraStormZL1]

I’m at the point that I’m ready to start upgrading for more power. My goal is around 700 WHP while keeping it still streetable, but I’m a little lost where to start even after reading tons of threads and watching many videos. Everyone seems to have different opinions and thoughts on the matter, so I’m asking for some wisdom from those that been down this road.

Already have a Bora S-Type catback exhaust, Rotofab baby CAI, DSX custom lid and Mighty Mouse Mild Catch can with the Stock tune on Nitto 555 RII’s.
My initial thought is to start with Long Tube headers, 103 TB (which one?), Ported SC, Upper Pully and Tune. Maybe upgrade to the Big Gulp at that point? However I think that only gets me probably mid 600’s or so?

I do not want to do any sort of Flex Fuel or Methanol. I’m in an area where I don’t have access to Ethanol fuel and I’ve done Methanol on my Sierra and not a big fan.

The one thing I’m struggling with is going beyond the aforementioned mods by cracking open the engine to do a cam, etc. I love the idea of the cam and that LOVE that sound, while adding stronger internals and more HP. Just not sure I want to go down that path. Is it worth it?

[SOCAL.M6.ZLE]

Hey Sierra Storm, welcome to the forum! Love the question, surely we all have some things we wish we would have done differently... I for one, have several... which is why I love helping to consult people new to the platform.

As you may know, there are more ways to mess your car up than not... and the paths to success are narrow when it comes to parts selection, installers and tuners.

In general, you are on the right track starting with headers (lots of caveats here also) Also understand the reluctance to opening the motor, although the benefits it provides are second to none when it comes to making efficient power and adding that visceral choppy idle...

That said, PM sent, happy to jump on a call to discuss in more detail (besides I am a slow typer)

[Z OH 6]

Originally Posted by SierraStormZL1

I’m at the point that I’m ready to start upgrading for more power. My goal is around 700 WHP while keeping it still streetable, but I’m a little lost where to start even after reading tons of threads and watching many videos. Everyone seems to have different opinions and thoughts on the matter, so I’m asking for some wisdom from those that been down this road.

Already have a Bora S-Type catback exhaust, Rotofab baby CAI, DSX custom lid and Mighty Mouse Mild Catch can with the Stock tune on Nitto 555 RII’s.
My initial thought is to start with Long Tube headers, 103 TB (which one?), Ported SC, Upper Pully and Tune. Maybe upgrade to the Big Gulp at that point? However I think that only gets me probably mid 600’s or so?

I do not want to do any sort of Flex Fuel or Methanol. I’m in an area where I don’t have access to Ethanol fuel and I’ve done Methanol on my Sierra and not a big fan.

The one thing I’m struggling with is going beyond the aforementioned mods by cracking open the engine to do a cam, etc. I love the idea of the cam and that LOVE that sound, while adding stronger internals and more HP. Just not sure I want to go down that path. Is it worth it?

Didn't see any mention of budget but 700whp is a fantastic goal on 93 octane because quite frankly, it's hard to use more power than that on street tires.

Having been there and done that with my 2021 ZL1, I can say that its easily doable and completely streetable. Mine had a Rotofab Big Gulp intake, 103mm throttle body, Kong ported blower, 9.45" DSX lower pulley, 2" Kooks headers and GESI high flow cats, Mighty Mouse Wild catch can, AFCO heat exchanger upgrades, ECM tune and the car made 697whp. I ran that setup for 4 years without any issues at all and I sold the car last year to a good friend of mine that is still driving it today with that setup without any issues.

I bought a 2024 CT5-V Blackwing in July 2025, obviously it has the same engine but makes just slightly more power from the factory. I went a different route with this car because I didn't want headers this time around. I went with a JLT 5" intake, 103mm throttle body, Magnuson 2650 supercharger, 9.45" DSX lower pulley and 100mm upper pulley, DSX aux fuel pump, Mighty Mouse Wild catch can, ECM tune, and this car made 722whp on 93 octane.

So if I were asked which path I would take again, it would be the Blackwing mods. I think there's HUGE benefits to going with the Magnuson 2650 over a stock ported blower especially on 93 octane. This setup not only made more power but because of the Magnuson it won't heat soak nearly as much as the ported stock blower.

There is one more option though, you could add a FI interchiller to the stock ported blower and keep the temps under control. That's a solid option too but does add some complexity and more cost to the build.

[2023-SS]

Originally Posted by Z OH 6

I didn't want headers this time around.

why did you not want headers? they seem like the FIRST thing everyone does.

I really some on my SS, but IDK if i want to take it apart, it just feels good & reliable now.

[ZLRob]

Originally Posted by 2023-SS

why did you not want headers? they seem like the FIRST thing everyone does.

I really some on my SS, but IDK if i want to take it apart, it just feels good & reliable now.

I'm going to assume he said this time around because he has done it before. I'm also going to assume he is similar to myself who has had a Chevy V8 who felt that having headers turned into an absolute nightmare because of burning plug wires, wiring harnesses, fitment issues, or possible leaks that occured throughout his ownership of them.


Can't say I blame him. It's reasons like what I highlighted above as to why I certainly don't want to mess with them again.


As for you OP, if you are needing to stick to standard gasoline that will potentially limit your power output production out of most efforts unless you get a very efficient air moving cam and do everything you can to keep boost output A. Low and B. Under proper thermal control whereas to not cause issues where you can run into knock (even false knock) and timing pull due to blower heat soak.


If you are looking to make quick and easy HP without having to change much, you may need to do the old fashioned 2650 supercharger upgrade, as that will keep your MAT temps low, due to lower boost production which will make more power than the 1740 stock supercharger. Only problem with that is that it will require a larger lower pulley or a smaller upper to regain that punchiness down low that the stock supercharger is known and loved for.


Too many variables and too many different ways you can skin the proverbial cat to make the power you want to get to 700. It's also difficult to guide you without the ability to have you run E85 (I understand access is limited or non existent where you live). You may need to talk with someone like Gabe to set yourself up a game plan as far as what mods fit you or not.

[Z OH 6]

Originally Posted by 2023-SS

why did you not want headers? they seem like the FIRST thing everyone does.

I really some on my SS, but IDK if i want to take it apart, it just feels good & reliable now.

Honestly because headers make these cars extremely loud which is something I got tired of in the ZL1 and not something I wanted in the Blackwing. Another reason is that for my goals of around 700whp, the stock exhaust manifolds aren't as restrictive as people think they are at that level, and the stock manifolds are a tri-Y design which typically makes more power under 6K rpms. A 4 into 1 header design will make slightly more peak power but it typically comes around 6K+ rpms.

Case in point, my car made 722whp with the stock exhaust manifolds and cats. The Blackwing in the link below made almost exactly the same power but this car has headers and no cats and all other mods being the same as mine. FHP is a very good shop in Florida so I trust their results.

[Z OH 6]

Originally Posted by ZLRob

I'm going to assume he said this time around because he has done it before. I'm also going to assume he is similar to myself who has had a Chevy V8 who felt that having headers turned into an absolute nightmare because of burning plug wires, wiring harnesses, fitment issues, or possible leaks that occured throughout his ownership of them.


Can't say I blame him. It's reasons like what I highlighted above as to why I certainly don't want to mess with them again.


As for you OP, if you are needing to stick to standard gasoline that will potentially limit your power output production out of most efforts unless you get a very efficient air moving cam and do everything you can to keep boost output A. Low and B. Under proper thermal control whereas to not cause issues where you can run into knock (even false knock) and timing pull due to blower heat soak.


If you are looking to make quick and easy HP without having to change much, you may need to do the old fashioned 2650 supercharger upgrade, as that will keep your MAT temps low, due to lower boost production which will make more power than the 1740 stock supercharger. Only problem with that is that it will require a larger lower pulley or a smaller upper to regain that punchiness down low that the stock supercharger is known and loved for.


Too many variables and too many different ways you can skin the proverbial cat to make the power you want to get to 700. It's also difficult to guide you without the ability to have you run E85 (I understand access is limited or non existent where you live). You may need to talk with someone like Gabe to set yourself up a game plan as far as what mods fit you or not.

I had no issues with the Kooks headers other than the huge increase in sound. Mine were Jet Hot coated with the 2500f coating so they were always cool and I never had issues with leaking or fitment. They just made the car too loud and after a few years, I just got tired of it.

I was worried about a loss of torque lower in the rpms with the Magnuson 2650 but that has not been the case at all. In fact, it makes gobs of torque very early and maintains and extremely flat torque curve. I'm sure the power curve is slightly different from a ported stock blower but in my experience between the two blowers, the difference is not noticeable enough that left me regretting the 2650. In fact, it makes traction easier on street tires. The power delivery on the 2650 is very linear and very predictable. Throttle response is instant at any rpm.

[SierraStormZL1]

Thanks for the input guys and @SOCAL.M6.ZLE I have yet to read your message. This site is so flaky as of late that I feel I get one good attempt a day to read or post without it timing out repeatedly

@Z OH 6 - Funny you mention LTH, I too was questioning going with them due to the increased sound and with a convertible, I'd imagine it'd even be worse. Is there anyway to tame that down with like maybe resonators or swapping out mufflers to a reasonable level? What would I lose by not adding LTH aside from the ~30ish HP?

I'd like to keep the current SC, but I understand the trade off. I also looked at increased cooling by swapping out the Heat Exchanger and tank. Seems like a meaningful upgrade given the poor cooling of the stock one especially if I'm going to push the stock system harder.

Looking at Kong's porting page it seems I have two options there. Regular porting or X-port. Sounds like the X-port from what I can derive can deliver more power, but is linked to cracking the case and getting a cam, etc. So I have some things to think about there.

As for budget, idk, I was hoping to stay under 10k this year, but I first have to figure out what exactly it is I want to do on the first round or do I wait, save up and go for it all the next year.

Should I just do the regular SC Port, TB, pulley, CAI and maybe LTH this year and then see where i'm at. Then maybe next year do the cam, X-port, heat exchanger, etc. Or is that going to cost me alot more in the long run?

[Z OH 6]

Originally Posted by SierraStormZL1

Thanks for the input guys and @SOCAL.M6.ZLE I have yet to read your message. This site is so flaky as of late that I feel I get one good attempt a day to read or post without it timing out repeatedly

@Z OH 6 - Funny you mention LTH, I too was questioning going with them due to the increased sound and with a convertible, I'd imagine it'd even be worse. Is there anyway to tame that down with like maybe resonators or swapping out mufflers to a reasonable level? What would I lose by not adding LTH aside from the ~30ish HP?

I'd like to keep the current SC, but I understand the trade off. I also looked at increased cooling by swapping out the Heat Exchanger and tank. Seems like a meaningful upgrade given the poor cooling of the stock one especially if I'm going to push the stock system harder.

Looking at Kong's porting page it seems I have two options there. Regular porting or X-port. Sounds like the X-port from what I can derive can deliver more power, but is linked to cracking the case and getting a cam, etc. So I have some things to think about there.

As for budget, idk, I was hoping to stay under 10k this year, but I first have to figure out what exactly it is I want to do on the first round or do I wait, save up and go for it all the next year.

Should I just do the regular SC Port, TB, pulley, CAI and maybe LTH this year and then see where i'm at. Then maybe next year do the cam, X-port, heat exchanger, etc. Or is that going to cost me alot more in the long run?

Resonators won't do anything to lower the volume since they don't have packing in them, they are simply designed to tame resonant frequencies which can cause some raspiness or drone. For people that want headers, the quietest option is going to be leave the stock suitcase muffler since its the largest muffler available for these cars. It will sound relatively tame at part throttle with the valves closed but it will certainly be much louder with the valves open and at WOT.

The Kong X-port is more efficient, but you will shift the torque curve upwards because to gain that extra efficiency, the X-ported blower has much more material removed internally which affect the lower rpm efficiency and power curve. You don't need a cam to run the X-port blower.


As for your future plans, I certainly would not pay for a Kong ported blower and then pay for the X-port again later. I would do it one way or the other once and be done with it. There's nothing wrong with the standard Kong porting, and pullies can certainly get you to 700whp without any issues. The biggest issue is just that staying on 93 octane at 700whp means that you will have to spin the blower a bit harder and it will generate more heat which is why you will absolutely need headers and upgraded heat exchangers and a auxiliary cooling tank.

[ZLRob]

Originally Posted by SierraStormZL1

Thanks for the input guys and @SOCAL.M6.ZLE I have yet to read your message. This site is so flaky as of late that I feel I get one good attempt a day to read or post without it timing out repeatedly

@Z OH 6 - Funny you mention LTH, I too was questioning going with them due to the increased sound and with a convertible, I'd imagine it'd even be worse. Is there anyway to tame that down with like maybe resonators or swapping out mufflers to a reasonable level? What would I lose by not adding LTH aside from the ~30ish HP?

I'd like to keep the current SC, but I understand the trade off. I also looked at increased cooling by swapping out the Heat Exchanger and tank. Seems like a meaningful upgrade given the poor cooling of the stock one especially if I'm going to push the stock system harder.

Looking at Kong's porting page it seems I have two options there. Regular porting or X-port. Sounds like the X-port from what I can derive can deliver more power, but is linked to cracking the case and getting a cam, etc. So I have some things to think about there.

As for budget, idk, I was hoping to stay under 10k this year, but I first have to figure out what exactly it is I want to do on the first round or do I wait, save up and go for it all the next year.

Should I just do the regular SC Port, TB, pulley, CAI and maybe LTH this year and then see where i'm at. Then maybe next year do the cam, X-port, heat exchanger, etc. Or is that going to cost me alot more in the long run?

For your header stuff you can add a tunnel muffler. Tons of people have done it, and it's certainly doable on yours. That should chill out drone if you have any.


As for the ported blower, look into Jokerz full tilt. It is designed to keep the factory style blower power and throughout the entire RPM range and is designed for applications within the power range that you are looking to be in up to around 900 WHP. That verbiage comes straight from Brett himself at Jokerz and after running his ported blower for close to about a year and a half now, that has been exactly my experience.

[Z OH 6]

Originally Posted by ZLRob

For your header stuff you can add a tunnel muffler. Tons of people have done it, and it's certainly doable on yours. That should chill out drone if you have any.


As for the ported blower, look into Jokerz full tilt. It is designed to keep the factory style blower power and throughout the entire RPM range and is designed for applications within the power range that you are looking to be in up to around 900 WHP. That verbiage comes straight from Brett himself at Jokerz and after running his ported blower for close to about a year and a half now, that has been exactly my experience.

You can run a tunnel muffler but it does add a good bit of weight, as well as it's a REALLY tight fit in that tunnel, I ran mine that way for a few months with an AWE touring catback and it was certainly much quieter but I didn't like the sound at all.

I've ran Jokerz and Kong ported blowers, I doubt there's much difference between them and they both do good work, the only difference is that I think Jokerz ported blower performs like the Kong standard port. I don't think Jokerz has anything like the Kong X-port which is capable of over 1000whp. Synergy Motorsports is another company that I've heard does great port work but I have no personal experience with them.

[JSH]

I did CAI, heads and valvetrain, and LT first, and that longblock ultimately made 1000+ on race gas.

Originally Posted by SierraStormZL1

I’m at the point that I’m ready to start upgrading for more power. My goal is around 700 WHP while keeping it still streetable, but I’m a little lost where to start even after reading tons of threads and watching many videos. Everyone seems to have different opinions and thoughts on the matter, so I’m asking for some wisdom from those that been down this road.

Already have a Bora S-Type catback exhaust, Rotofab baby CAI, DSX custom lid and Mighty Mouse Mild Catch can with the Stock tune on Nitto 555 RII’s.
My initial thought is to start with Long Tube headers, 103 TB (which one?), Ported SC, Upper Pully and Tune. Maybe upgrade to the Big Gulp at that point? However I think that only gets me probably mid 600’s or so?

I do not want to do any sort of Flex Fuel or Methanol. I’m in an area where I don’t have access to Ethanol fuel and I’ve done Methanol on my Sierra and not a big fan.

The one thing I’m struggling with is going beyond the aforementioned mods by cracking open the engine to do a cam, etc. I love the idea of the cam and that LOVE that sound, while adding stronger internals and more HP. Just not sure I want to go down that path. Is it worth it?

[AZIROC]

Im in the same boat OP. Im looking for around 700rwhp but dont really want to drop the koney for a cam. Unfortunately E85 is not as easily accessible and I don't want to so meth either. Right now I have your "basic" zl1 mods... Kooks LT (no cats) into a borla S-type, regular roto, ported tb and a 2.3 upper ive been told if I get the xport id have to get a cam for the fueling... so now a 6k cam swap (9-10k to do it right) goes up another 2k cause of the ported blower cost .. and I really dont want to drop 10k+.

[Revalot]

BTR is coming with a new porting for superchargers that's supposedly better than all others in a few months. Here's what I installed yesterday, magnuson 2650R on a LT4 6 speed manual with CAI and man its nice, so cool on temps, you can put your hands on the blower after a 30 minute drive and it's not hot. A BTR stage 2 supercharger cam, springs, push rods and katech oil pump. All on stock manifolds, looking for 800 hp and that's it. Just a nice car that's better than new on the performance side.