I have a 2017 C7 Grand Sport with auto. Looking to add an xipe that deletes the secondary cats. No looking to go with new long tube headers. I found an xpipe that does this and it would connect to the stock primary cats. (I will be going with a new AWE track edition 3" axleback system. However in my search I found replacement down pipes that have high flow cats that I assume connect to the end of the stock headers, Also found some down pipes that delete the primary cats entirely. I have to get a tune regardless. I have been told the primary cats on the C7 flow pretty good. I just dont know that I want to go catless due to emission checks etc. Also don't know that there would be that much of a HP difference between going with a new down pipe with high flow cats or just stick with stock. Reason I am not going with new long tube headers is $$ and again the emissions crap. I have also been told that the stock primary cats will help the sound by deepening the tone.

If any of you have gone with the new downpipes with high flow cats would love to know what you thought about them using the stock headers.

TIA

 

Light the $100 bills on fire and you’ll get the same thrill. Total waste of time and money to replace the OEM main cats with aftermarket cats.

If you replace the intermediate pipe with one that doesn’t have the secondary cats, you get a little more sound and depending on brand it’ll change the tone. You do Not need a tune. The secondary cats are not monitored.

 

So in your opinion going with a new 3" donw pipe with high flow cats is a waste? What about the 3" catless downpipes?

 

in either case, you’re just spending money to spend money