[KyleP_1LE]

Has anyone had issues at all after a secondary cat delete (resonator) ? I am about to get mine removed and I just wanted to see if anyone had issues. I know it shouldn't throw a code as they are downstream of any O2 sensor. I just want to make the car a little louder but maintain the use of the NPP valves and this seemed like the easiest way.

[WhiteMale]

Its known to not have any issues like codes and such.

[shippingguy]

Originally Posted by KyleP_1LE

Has anyone had issues at all after a secondary cat delete (resonator) ? I am about to get mine removed and I just wanted to see if anyone had issues. I know it shouldn't throw a code as they are downstream of any O2 sensor. I just want to make the car a little louder but maintain the use of the NPP valves and this seemed like the easiest way.

It’s makes a nice difference in the tone. No real performance gain, but sounds way better. You will not have any issues unless your installer does not weld properly and there is a leak around the weld. Not a tough job for any exhaust mechanic.

[Dynamical]

Through my research I have found nobody with codes from doing that. I'm actually thinking about doing that too.

[KyleP_1LE]

Originally Posted by Dynamical

Through my research I have found nobody with codes from doing that. I'm actually thinking about doing that too.

Seems like a cheap easy way to get a little better sound. I found an X pipe meant to delete them but it seems like a ton of money in comparison to getting someone to just weld a piece in-between.

[Ventmaster]

For a short time Borla made the part #60606 available to achieve a 2nd cat delete and improved X-pipe bolt on as an inexpensive alternative to a full exhaust system change. At that time, I think it was about $600 for the X-pipe vs. $2-3K for a full system.
I was fortunate to grab one and in some early exhaust discussion told the folks here on C6 to "get one while you can". I've heard there is another perf. exhaust company offering a similar part and all I can tell you is I'm still thrilled with the result of my Borla combined with the NPP exhaust option. In Track mode it is plenty loud enuff for me and when I visited my son in California, I made sure not to draw too much attention for fear of some kind of punitive action by that state's police!
Probably no performance improvement, but it sounds great IMHO.
Also, no CEL's or drivability issues with this mod.

[Dynamical]

Originally Posted by KyleP_1LE

Seems like a cheap easy way to get a little better sound. I found an X pipe meant to delete them but it seems like a ton of money in comparison to getting someone to just weld a piece in-between.

I just put an AWE track axleback on. I wish they still made the secondary delete but they dont. So I was looking at other options. MRT still makes one. I was considering entertaining that. As much as I want to go wild with a full header system and mods, I'm not sure if I wanna blow the warranty. Figured a secondary delete system would be my compromise to keep me happy until the warranty gets deleted
But IDK if I can make it that long!
I'm curious, which one are you looking at?

Originally Posted by Ventmaster

For a short time Borla made the part #60606 available to achieve a 2nd cat delete and improved X-pipe bolt on as an inexpensive alternative to a full exhaust system change. At that time, I think it was about $600 for the X-pipe vs. $2-3K for a full system.
I was fortunate to grab one and in some early exhaust discussion told the folks here on C6 to "get one while you can". I've heard there is another perf. exhaust company offering a similar part and all I can tell you is I'm still thrilled with the result of my Borla combined with the NPP exhaust option. In Track mode it is plenty loud enuff for me and when I visited my son in California, I made sure not to draw too much attention for fear of some kind of punitive action by that state's police!
Probably no performance improvement, but it sounds great IMHO.
Also, no CEL's or drivability issues with this mod.

I would of grabbed the Borla right now SMH
I heard quite a few people say the secondary delete does't do much for sound. You say it does?

[Ventmaster]

Yes, even though the secondary are smaller, it's still a cat with like 600 channels or cells per square inch (I am totally blowing smoke here! I can't remember what a factory spec cat has!). That does a little muffling. That's why some Camaro owners prefer to just run a straight pipe behind their cats. After passing thru both cats, it's not THAT loud IMHO of course.
But the primary cats with a NPP option works well for me.

[FlukeSS]

Originally Posted by KyleP_1LE

Seems like a cheap easy way to get a little better sound. I found an X pipe meant to delete them but it seems like a ton of money in comparison to getting someone to just weld a piece in-between.

Speed Engineering $250 + install cost. I guess it might be considered a ton of money, but seeing as I'm a broke joke and not mechanically inclined it was an easy decision.

[KyleP_1LE]

Originally Posted by FlukeSS

Speed Engineering $250 + install cost. I guess it might be considered a ton of money, but seeing as I'm a broke joke and not mechanically inclined it was an easy decision.

The only one I saw was the GT Haus one for just shy of $1000 USD.

[Booher]

I had one on my 17 2ss and now have one on my 19 zl1, both going to sw axleback. It was definitely louder on the ss than with the cats, not huge but very noticeable. It was louder with a higher pitch. On the zl1, I feel, it made more of a difference, still nothing huge like adding an axleback, but more than the past one. Once again, it gave a little higher pitch but when downshifting it sounds really good, I can only describe it as "barking sound", not like a dog, lol. I believe you gain 2.5-5 hp for loosing the secondary cats, as they are still a restriction. Deleting main cats is about 15hp, pls someone correct me if I'm wrong, been a while. I used the borla ones, the speed engineering ones have fitment issues if I remember correctly, and have to remove or change out a lower brace due to clearance. Best bet nowadays, is to try and find a shop to do it, which could be tough. Ive heard if you take them out yourself, then take it to a shop, they can install it, because it wasn't in the car and they aren't removing anything, aounds risky, though, lol. You could also cut them out, beat out the core so it's more free flowing, and use some vibrant exhaust clamps to seal it up with no leaks. Bonus, it looks factory and won't mess with inspections. I think they test for carbon dioxide, among others, but secondary cats are for carbon monoxide, which you should be able to pass with.

[KyleP_1LE]

Originally Posted by Booher

I had one on my 17 2ss and now have one on my 19 zl1, both going to sw axleback. It was definitely louder on the ss than with the cats, not huge but very noticeable. It was louder with a higher pitch. On the zl1, I feel, it made more of a difference, still nothing huge like adding an axleback, but more than the past one. Once again, it gave a little higher pitch but when downshifting it sounds really good, I can only describe it as "barking sound", not like a dog, lol. I believe you gain 2.5-5 hp for loosing the secondary cats, as they are still a restriction. Deleting main cats is about 15hp, pls someone correct me if I'm wrong, been a while. I used the borla ones, the speed engineering ones have fitment issues if I remember correctly, and have to remove or change out a lower brace due to clearance. Best bet nowadays, is to try and find a shop to do it, which could be tough. Ive heard if you take them out yourself, then take it to a shop, they can install it, because it wasn't in the car and they aren't removing anything, aounds risky, though, lol. You could also cut them out, beat out the core so it's more free flowing, and use some vibrant exhaust clamps to seal it up with no leaks. Bonus, it looks factory and won't mess with inspections. I think they test for carbon dioxide, among others, but secondary cats are for carbon monoxide, which you should be able to pass with.

Did you notice any negatives? One shop told me that I will dump a ton of gas without them since their main job is for heat when the primary's are in startup phase and they said I will throw codes due to that.

[tomster]

I've deleted the secondary cats on both my ZL1 1LE's (2018 & 2022) I have owned. You get a slightly louder tone, No drone, quite a bit more crackle on de acceleration, and no real noticeable difference in fumes.

I deleted both cats on my 13 ZL1 and on my 18 CTS-V. You get a much louder tone, still no drone, lots of crackling pop, however you'll definitely notice the exhaust smell. Depending on what else you have done you may even get some flames pop out the tailpipes on de acceleration when you delete both cats. (obviously requires a tune to keep the check engine light off)

As far as horsepower I don't believe you get anything from deleting the rears. Fronts may give you 5 to 10 horsepower without a tune.

[tomster]

Speed engineering is the only company I know of currently making the secondary cat delete /x pipe. The only problem I had was getting it to tuck up high enough to go over the tunnel brace. I ended up buying a tunnel cross brace that has a little drop in it from Halo..
https://speed-engineering.com/collec...16-6-2l-engine

https://www.phastekperformance.com/H...halo-cdtg6.htm