[Sweet15]

So, I've got all ordered and on the way.

Whipple, LT4 HPFP, LT4 injectors, DSX Aux fuel pump kit, Roto-fab dry CAI, Mighty Mouse CC, NGK 6509 plugs, and LS3 front seal.

So my question is about headers / exhaust. I have a 18' 2SS A8 vert w/NPP so I want to keep it kind of quiet. Had a 15' SS that was S/C and cammed with Stainless Works that was pretty loud, had to pull over to talk on the phone LOL.

So getting mixed opinions on needing headers / exhaust. Is it necessary; some say stock set up is pretty good up to about 700 wheel hp. As a vert I would want to get catted if I went with headers due to the fumes. I would like to get over 600 to the wheels, so I think I should be able to tune it between 8-10psi with the fuel upgrades, which should get me there or close ? Don't want to do meth or E85, will be tuning to 93.

I looked at TSP 2" w/ catted to NPP; however being a vert they suggested the 1 7/8 instead for fitment. Some other brands cat back/axle back won't even work with a vert from what I saw.

So, is it necessary or will the stock set up be fine ? No sure the word necessary is right. Maybe is it needed ?

Thanks all ...

[KingLT1]

The only thing that really needs to be addressed is the primary cats. Even then if the tuning is correct you can make a bit more than 600whp with no issues on stock exhaust. Laynlo and toohighpsi have both made over 700whp on bone stock NPP exhaust. Some have melted the cats with less power, but again tuning and how much excess fuel is dumping into the cats will play a factor.

I am also getting ready to install my Whipple. My setup will consist of: CA performance cat deletes(retaining the secondary), Rotofab dry, Ported TB, LT4 Injectors, LPE HPFP, ZL1 intank, and JMS booster.

I really like the CA delete pipes with secondary in place. In touring the exhaust is nice and quiet, in sport it is a bit louder and screams pretty loud at WOT. No drone either way. The issue is finding the delete pipes. Nobody is currently making a set that bolt's in and retains the secondary.

I do think a set of TSP 1 7/8 with high flow cats would get you what you want either way. The main thing is to have a high flow cat or resonator pre muffler for added sound control.

[oldman]

1 and 7/8 with high flow cats, for figment and heat, you still have to wrap the starter.

If you go ca front deletes, I would move the rear 02 to behind the second set of converters, that way you won’t have ready monitor issues at smog time.

Some body should do cat head pipes that remove both of the factory cats with 5 total ow bungs.

[steelheadrob]

I have pretty much the same set up you are doing except I have the TPS 1 7/8" with the high flow cats. The set up you are looking at will get you to the 600 number you want. If you want more without going to e85 or meth then you will need to address the exhaust. Jhunsberger was right at 600 then did the cat delete and added around 20hp more. My dyno numbers are a little higher with the TSP 1 7/8" & high flow cats. I am happy with the sound I got, cold start is louder, louder when I get on the throttle, sounds like stock cruising down the freeway in tour mode, no drone, no fumes. I posted a install video on Youtube if you skip to the end I included a few sound clips.

[oldman]

Originally Posted by Sweet15

So, I've got all ordered and on the way.

WSo getting mixed opinions on needing headers / exhaust. Is it necessary; some say stock set up is pretty good up to about 700 wheel hp. ...

700 wheel or about 800 engine, don't think anybody says it is "fine". Need is hard to qualify. I'm building for 709 whp, and anything that reduces pumping losses is a win all the way around. 1 and 7/8 headers high flow cats. Sure it can be done by cranking the boost, but it is much harder on the engine. Freeing up say 2 PSI or boost or 45 HP at this range is a no brainer IMO. So can 700 wheel be done by cranking the boost, bone stock exhaust? Probably so. Is it "fine".. um I would not think so. It clearly is a more stress package then reducing pumping loss.

Now just at 700 WHP almost 800 engine, front cat deletes probably be "ok", I would do as a minimum:
http://www.neweraperformanceparts.co...ete-pipes.html

delete all 4 and have a shop weld in two highflow metal cats. One of the reasons I would consider this is there is a lot of heat under this hood, heck you may consider coated factory headers, the above 4 cat delete and weld in two metal cats is optimal in terms of weight, room and heat.

Still when all was said and done, I went from CA front cat deletes to 1 and 7/8 headers and high flow cats. other than heat, I love the setup. And no I don't want to sell the CAs...

So is the question surrounding affordability? IMO, there is no 700 WHP on the cheap. If you are going to run stock pistons, you best be looking at reducing the heat load on the engine.


Lingenfelter package adds a whole lot from 720 engine to 800 engine, including headers and high flow.

Hennesy uses STD wheel HP to overhype their figures, but if you subtract 50 hp from their 750 and 850 packages, you can see like Lingenfelter they add headers, don't like any company that publishes STD especially on a FI engine but I digress.

[SC88]

I'm running the Stock NPP, Kooks LT's & No cats and wish the car was louder. I can have plenty of phone conversations through Bluetooth in tour mode with no issues.

I also make over 700whp on my street tune and have made over 800 when testing.

[oldman]

Originally Posted by SC88

I'm running the Stock NPP, Kooks LT's & No cats and wish the car was louder. I can have plenty of phone conversations through Bluetooth in tour mode with no issues.

I also make over 700whp on my street tune and have made over 800 when testing.

even with my 709 whp target, I'm stock after the cat, and it is the base system too crush pipes and all. I spent my money on more fuel and E85. My exhaust is just about right, not too loud, I do wish I had a slight bit more cam sound.

Oh I really like Cunningham's progression:
http://cunningham-motorsports.com/pr...f067a16fd83e69
1) supercharger tune
2) supercharger cam headers tune
3) supercharger cam headers E85 tune

to me this is easier on the stock pistons then just upping the boost. base, base plus breathing and fuel, the e85 with about the same or just a tad bit more boost.

I know the cam change is expensive, I'm just saying to my mind this is the most logical sequential build.

[Jhunsberger]

Like steelheadrob mentioned, I am running basically the same setup as you and him, with the stock exhaust. Tuner said the cats were getting hot after tuning on the dyno, mind you this probably built up some excessive heat with multiple dyno pulls. They suggested (should have listened) headers to eliminate the cats. At the time I didn’t want to spend the money for headers and just went with NEP cat delete pipes with stock exhaust. I HATED the sound of the exhaust with this setup with all the cats deleted thru the stock exhaust. So, I did Borla ATAK cat back with NPP, and added their mid pipe resonator. I think the resonator made the difference for me. I was much happier with the exhaust note of the Borla system and NEP pipes. It is very loud on startup, down shifts and when you stand on it. The cats really quiet it down. This is where my exhaust sits now.

Now looking back, I regret not doing the headers right off the bat, considering I have a set of 2" kooks no cats jet hot coated on order for the pursuit of more HP, so the cat delete pipes were a waste of $. My thought is with forced induction just about any cat runs you the risk of melting down and giving you problems. So, it’s a matter of $ and your personal taste of how you want the exhaust to sound. Even the high flow cats I think will eventually break down and cause issues, i could be wrong.

Good luck with your build, hit us up anytime, that is what we are all here for. This forum was so very helpful with my build. Research and ask questions.

[oldman]

Same way, CA front cat deletes and then headers with no cats, the engine really hated anything under 2000 RPM, normal driving was terrible. Put the high flows in.. all good. I too thought about the adding Borla mid pipe resonators.... Since this is a street car with 5 second WOT blast, I'm OK with cats. I think the no cats is really an issue with the M6 with no valves in the exhaust

[laynlo15]

Ran mine with stock exhaust till just recently when I built the new motor. Haven't run it yet with the long tubes. So, I'd say yes.

[KingLT1]

Originally Posted by Jhunsberger

Like steelheadrob mentioned, I am running basically the same setup as you and him, with the stock exhaust. Tuner said the cats were getting hot after tuning on the dyno, mind you this probably built up some excessive heat with multiple dyno pulls. They suggested (should have listened) headers to eliminate the cats. At the time I didn’t want to spend the money for headers and just went with NEP cat delete pipes with stock exhaust. I HATED the sound of the exhaust with this setup with all the cats deleted thru the stock exhaust. So, I did Borla ATAK cat back with NPP, and added their mid pipe resonator. I think the resonator made the difference for me. I was much happier with the exhaust note of the Borla system and NEP pipes. It is very loud on startup, down shifts and when you stand on it. The cats really quiet it down. This is where my exhaust sits now.

Now looking back, I regret not doing the headers right off the bat, considering I have a set of 2" kooks no cats jet hot coated on order for the pursuit of more HP, so the cat delete pipes were a waste of $. My thought is with forced induction just about any cat runs you the risk of melting down and giving you problems. So, it’s a matter of $ and your personal taste of how you want the exhaust to sound. Even the high flow cats I think will eventually break down and cause issues, i could be wrong.

Good luck with your build, hit us up anytime, that is what we are all here for. This forum was so very helpful with my build. Research and ask questions.

I think NEP should offer a resonator included in their delete pipes for sound control since they delete all 4 cats.

[Sweet15]

Thanks guys, I really appreciate the input and exactly why I asked. Glad to see similar builds, would be curious to see dyno numbers for all for comparison. Thanks for letting me know about the front cat deletes as I was leaning towards that, but not now. I will probably end up doing the TSP 2" with high flows into the NPP. Not going to track it, just some spirited driving every now and then.

[Jhunsberger]

Be careful with the 2" TSP headers, i believe they state on their website that the 2" are real close to the steering shaft. In the end, glad you have a direction forward, good luck with your build. i think most of us have dyno info in our sigs.

Straight from their website:

*Please note that the 2" primary headers will have limited clearance around the steering shaft and the rest of the engine bay. Some customers may have to shift the engine over or dimple the headers to gain proper clearance because it is so tight. If you are concerned with this issue, we recommend purchasing our 1-7/8" long tube headers that provide better clearance.


*Additional modifications needed to fit convertibles.

Originally Posted by Sweet15

Thanks guys, I really appreciate the input and exactly why I asked. Glad to see similar builds, would be curious to see dyno numbers for all for comparison. Thanks for letting me know about the front cat deletes as I was leaning towards that, but not now. I will probably end up doing the TSP 2" with high flows into the NPP. Not going to track it, just some spirited driving every now and then.

[oldman]

Originally Posted by laynlo15

Ran mine with stock exhaust till just recently when I built the new motor. Haven't run it yet with the long tubes. So, I'd say yes.

was that with all 4 cats???