[Laststandard]

Originally Posted by dmcmahan60

Then just do an axle back. It has been shown on this forum where the crush is has little to no effect on performance. I completely understand about not wanting to touch the Cats for warranty reasons. Good luck.

Mishimoto tested and found the crush sections had no negative effect.

https://www.mishimoto.com/engineerin...he-crimp-myth/

[mggeyer]

I decided to void my warranty and go with Kooks 1,7/8 Headers , green cats , CAI and a tune. The car is considerably quicker and runs great. When installing the headers and green cats the secondary cats were removed. Car sounds great and definately LOUDER. I NEVER use tour mode and quiet the exhaust so I am now adding the AWE Cat backing touring exhaust with resonators. A full 3 ' exhaust with headers and high flow cats should definately improve flow and add small but not insignificant HP improvement. Testing has showed the the crush pipes had no affect on dyno numbers although they helped with drone. I have not yet installed the AWE exhaust yet so I hope I am as happy with it as I am with the current NPP system. It really sounds good now. I just want to complete the system, more air in more air in more air out! Good luck with your decision, but it sounds to me me that you enjoy your npp system now so Im not so sure I would be anxious to replace it, it works well. Different strokes for different folks.

[FNxR3DNECK]

I did Stainless Works 3" Catback, some will argue about the performance gain but I don't really care, I mainly did it for the sound. Very nice deep, rumbly tone (not raspy like Borla and others). It also retained the NPP which I wanted.

[Shawnqa800720]

The suitcase is part of your air diffuser system. Removing it can impact performance of the airflow engineering that went into making the 1LE a track beast. Best advice is to leave it alone. But, that said, I know leaving it alone is not something anyone on these forums is good at.

And voiding of warranty is like death and taxes - the only things that are guaranteed. If you modify from stock, GM can void your warranty. Not all dealerships will go that route, but all dealerships can if they want to if you change something.

[Blueclyde]

Originally Posted by Vannmike

All I'm trying to do is get the car a little louder, deeper sound with a few more gurgles from the engine. Do you think even that is too much for the 1le? And when you say trouble when removing cats, does that go for the secondary cats as well? Thanks for the advice

Removal of any part of the catalyst after treatment system is not advised. It will require a “tune” which is a change to the engine conteol module calibration. This will void your warranty and will likely be done by somebody who hacks in with one of these aftermarket tuners. Most of these tuners have no real background with what they are doing. I would not be so quick to pay somebody a bunch of money for a backdoor calibration hack required to install some over-priced aftermarket exhaust that will be “deeper” than the NPP system. This is an internet enthusiast forum and the experienced feedback I am provided you here will be the minority view.

[Whocares05050]

Originally Posted by Blueclyde

Removal of any part of the catalyst after treatment system is not advised. It will require a “tune” which is a change to the engine conteol module calibration. This will void your warranty and will likely be done by somebody who hacks in with one of these aftermarket tuners. Most of these tuners have no real background with what they are doing. I would not be so quick to pay somebody a bunch of money for a backdoor calibration hack required to install some over-priced aftermarket exhaust that will be “deeper” than the NPP system. This is an internet enthusiast forum and the experienced feedback I am provided you here will be the minority view.

No mainstream GM performance shop is "hacks". This isnt 1999 and we arent dealing with fast and furious honda fan boys soldering chips into the ecu.

You need to be a legitimate shop, pay shit tons of money to HP tuners, have an expensive ass dyno, pay rent and employees, etc etc.

Sure, there are tuning shops out there that may not know evwrything about these cars, but the vendors on here offering tuning services are legit and have safely tunes thousands of high HP GM vehicles.

All that said... only removing the primary catalytic converters will require tuning calibration. Removing the secondary converters wont need it. They are only there for cold start emmisions and are not even required by law.

[Blueclyde]

Originally Posted by Whocares05050

No mainstream GM performance shop is "hacks". This isnt 1999 and we arent dealing with fast and furious honda fan boys soldering chips into the ecu.

You need to be a legitimate shop, pay shit tons of money to HP tuners, have an expensive ass dyno, pay rent and employees, etc etc.

Sure, there are tuning shops out there that may not know evwrything about these cars, but the vendors on here offering tuning services are legit and have safely tunes thousands of high HP GM vehicles.

All that said... only removing the primary catalytic converters will require tuning calibration. Removing the secondary converters wont need it. They are only there for cold start emmisions and are not even required by law.

No disrespect to you, but nothing you say above is completely correct. I’m not going to take this thread down a back and forth debate rabbit hole and this will be my final response. HP Tuners is a hack through the factory ECM’s encryption key. Sure there are tuners that have tuned lots of cars to high horsepower. Some do it legall by following required procedures to certify their aftermarket system with EPA or CARB, but there are very few that do this. 99% of it is technically not legal and considered tampering, which is a violation of the Clean Air Act.

[Vtor_ZL1]

There is currently a case goign through courts regarding HP tuners and another 8-bit person who hp tuners stole their stolen code. "Hey you stole our stolen code" We had it first, why are you giving it away.


Look up cost of clear air violations... vw n their emissions defeating tunes. What HP tuners are doing is not much different. Oh no increasing emissions.


Enjoy it while it lasts. Tuner vs tuner crap is going to raise enough stink that they will all be run out of business. Remember bucky balls ?

[Boost Creep]

I've given this some thought, considered gutting the secondary cats, going the 60606 route, etc. What I've come up with is when warranty is less of a concern, just going to do long tube headers.

Better sound and power all in one mod.

[Laststandard]

Originally Posted by Shawnqa800720

The suitcase is part of your air diffuser system. Removing it can impact performance of the airflow engineering that went into making the 1LE a track beast. Best advice is to leave it alone. But, that said, I know leaving it alone is not something anyone on these forums is good at.

C'mon.. 80% of the people here will not have the car on track, and 99% who do go to the track will be doing non-timed events, or autocross where the speeds aren't high enough to matter.

[dmcmahan60]

Originally Posted by Laststandard

C'mon.. 80% of the people here will not have the car on track, and 99% who do go to the track will be doing non-timed events, or autocross where the speeds aren't high enough to matter.

Was not going to say anything about the other persons comment but coming from a 1LE owner you are correct.

[Boost Creep]

Originally Posted by Laststandard

C'mon.. 80% of the people here will not have the car on track, and 99% who do go to the track will be doing non-timed events, or autocross where the speeds aren't high enough to matter.

lol
And of those who are on a timed track event, will their driving be good enough and the car going fast enough where the aero of the suitcase muffler would make a noticeable difference?

[bullet3z]

The Borla 60606 is a great option and does exactly what you are asking for. It only removes the secondary cats and goes all they way back to the factory muffler. Think of it as a complete mid pipe. I am very happy with mine. It looks and sounds great when installed. No codes.

[Mdell2]

I did axel back and even though it sounds deeper, it's not much louder than my NPP. It's sounds great when you step on it but it's definitely not Dodge or Ford loud. I came from a mustang with Flowmasters and my 1LE doesn't even come close. I think it has to do with the ecm and tuning so if your not on the throttle, it's quiet no matter what. I too don't want to void my warranty or dump big $$$$ into an exhaust system, I just want a nice (louder) sound. Any advice is appreciated.