I took them out on like the 3rd day. Not much louder, a little bit more bass though.

 

Any noticeable gain in power? Do you still have your resonators in place?

Edit: Looks like you have a MY16 model - so no resonators. How loud is it with the mufflers open? Do you find yourself going back to the quieter mode often because of its volume?

 

Did you have some straight pipe welded in? And did it trigger a cel?

 

Should not cause a DTC, the OBD system only monitors the front cat.

 

Yeah I have 2 pipes put in. The secondary cats are not monitored in any way. Chop them out.

 

Thanks for the reply.

 

No power gain, not really louder, just a deeper tone. Mufflers have never been closed in since I drove off the lot and 5K miles.

 

Did it...sounds the way it should have from factory. No difference in drone or performance but the exhaust should proper

 

Ended up doing this with the solo axle backs. Amazing sound! Deeper, crisper, much better tone. Only louder when getting on it and cold start. I could not be happier.

 

Do you just go to a reputable exhaust shop and have them do this? What did you guys pay?

 

Lots of exhaust shops won't remove a cat. Fairly hefty fine for them if caught. Replace, yes. You might remove it yourself and get them to fab something up to fill the gap. I'd ask before showing up though. In a small town where you've known the muffler man for years, you can get a lot done. Big town where you don't know who you're dealing with (and the muff man doesn't either), good luck.

 

Sound clip on cold start from my phone

 

Sound clip on cold start from my phone

https://www.youtube.com/watch?v=VDQJZZFnnMY

That's sounds really good actually .....

 

I picked up my 16 from a friends dyno shop today after adding Kooks long tubes(1 7/8) and their midpipe setup today. 405hp and 376 torque on the ground. I recommend that setup and the sound is wonderful and it opens up the power nicely.....When the muffllers are on performance it sound kinda like nascar........Glad I did it !!

 

I have the same setup as TLH.SS and can agree that it sounds great. Ran me $90 at a local muffler shop. Adds deepness to the tone, little louder on cold start, and WOT sounds just right.

Solo axle back, secondary cat delete

 

im going in tommorow to ask about this on my 16, cant wait!!!

 

just got mine done and all i can say is holy cow it sounds great, really gives a beafy note off the line and scares the **** out of people when i start it up when they are right behind it.love it!!!

 

These cars sound the best on startup either way.

I still need to have this done. I did it on my old G8 GXP and it sounded pretty good, until I got Corsa and then that was in another league. Hah

 

So those of you that have done this on a 16 did you remove the 2nd H-pipe also? ( i guess i should say the first, the one that is next to the rear cats) Whats the freaking point in two? there's always a first for everything with GM! LOL

 

Yes he is right, it's a brace

 

I believe one of the h-pipes is in reality, just a brace.

 

was gonna say... that is ODD. Has anyone with a 2016 done this and everything else is stock? Just curious if this wakes up the NPP. I haven't pulled the trigger yet.

 

When I was searching for videos on a 2015 I came across this video:

 

****, cant really tell.

 

OK, so i bit the bullet. Took out the secondary cat and had an xpipe replace the H pipe... keeping everything else stock like bimodal etc. On tour you cannot tell a difference at all but on perf. ITS MUCH BETTER. its not loud and its not obnoxious, but its deeper and has a more open exhaust note. the way i wouldve expected it to be stock. So, now, i'll drive this for a while and if i feel im not happy with the new volume i may do high flow solo's with this setup. $70 and an hour of time. SIGN ME UP! Well worth the money.

 

https://goo.gl/photos/eJ7eEWreZtfVPuBQ7

 

That sounds really good. Did the X change the exhaust note/pitch at all at higher RPM?

 

Its much more refined, I felt like the stock bimodal sounded kindof like a glasspack cherry bomb at WOT... now it sounds like a performance muscle car. Very Pleased! and I added my RotoFab today! OMG love it!

Still think I may do the solo high flows tho for that extra volume

 

 

I'll put my two cents in, just got this done this past week. Along with the cats, also removed the resonator and added in x-pipe. Absolutely awesome sound change.

 

I'll put my two cents in, just got this done this past week. Along with the cats, also removed the resonator and added in x-pipe. Absolutely awesome sound change.

https://youtu.be/VO6q7vnxOmM

That sounds really good. Who did the work, and do you have any pics of the underside of the car?