I have a 2012 base C6. Just added Corsa Xtremes. No headers or anything else. My cars sound is being blown out of the water by my buddy's S550 5.0 with Corsa. What is holding my car back? I don't have a way to get under the car and actually see what's there.

 

Problem is you have 4 cats in the exhaust system (2 per side, with one after the other per side). Hence the cats will quiet the system down more than the oem mufflers instead.

 

Headers and x-pipe will wake it up!

 

Are they both connected to sensors or can I remove one from each side?

 

GM added the second set of cats in line at the X pipe location to lower emissions.



So if you remove the back cats, then you need fill in the cat section on the X pipe (or just replace the X pipe).
Corsa X pipe top, that runs around $400


As for the O2 sensors, only the front cats are monitored with sensors.

Hence the O2 sensor just before the front cats are used for closed loop sensoring for the engine tune, and the O2 sensor just after the front cat is used to just monitor the cat only.

I bring this up, since when you install headers with high flow cats after each header collector (which don't muffle the sound anywhere near as the stock cats), you only leave the pre cat 02 sensor in play, and the after cat o2 sensor is deleted in the tune isntead (not used).

The reason for this, the high flow cat is moved down line away from the heads (after the header collector isntead with headers) and his causes the high flow cat to be less effective than the OEM cat close to the heads isntead. So with the less effective high flow cats (still good enough to keep the car from stinking of un-burnt fuel every stop light) the differential reading pre and post cat will not be great enough, and the car will throw codes since the High flow cat is not being as effective as the OEM cat was isntead (not wide enough readings of the two sensors).

So rear cat deletes will add a little more sound (still have the front OEM cats in play) , but going to headers system with High flow cats (just 2, and one per side) will end up with gaining around 25HP with a tune, and way more exhaust sound instead.


As for a header system with high flow cats and new X pipe, an stainless steel OBX system is about $850, while an American made stainless steel system can run up to $2K instead (plus labor if you are not going to install it yourself). And no, with both header systems using 1 3/4" header pipes (what size you want to use, and not 1 7/8" header pipes isntead), one will not put out more power than the other.

How the OBX header system with cats comes, and about $850


As for a tune after you change out just the X pipe to remove the rear cats, shouldn't be needed, but you leaving about 15HP on the table if you are running the stock tune still. As for if you add headers, yes will need to have the car retuned, but if you add the 15Hp on the table from the stock tune, and the 25hp that the headers will add as well, then here the tune will yeild you about an extra 40HP instead.

And understand why the headers (collectors) are gaining you the extra 25hp in the first place!!!
The high flow cats only rob you about 3hp only, so you want to run them to prevent the un-burnt gas out the exhaust stinking the car up every stop light.

 

X-pipe is a good route to go