[gangir5]

Ok so heres the story...I have a 2012 2SS/RS LS3 coupe with 13K miles. I bought a Stainless Works Catback 3'' system with the x-pipe and turbo chambered mufflers. Bolted it on, no problems...I recently decided to spend some more cash and ECS from NJ hooked me up with a great kit that I installed myself. I got ARH 1 7/8 headers with high-flow cats, mail order tune, CAI intake, and 160 stat. Everything is installed, no problems. Started the car up, idle is fine, great sound, reves up to 5k no problem (rev limited when parked) smooth, no odd sounds.

Now driving...heres the problem...under a moderate load under 4k revs it pulls fine...under WOT I hear this clunking metal noise from the muffler area...(super loud) and its only when my foot is too the floor and I'm pulling to high RPM range. Rechecked everything, no codes, sensors are fine, plugs and wires all tight. When I gun it, the car loses back pressure seems like...and almost sounds like I am running a "lumpy" cam when at idle...except this sound is only under a load. It sorta hesitates and falls on its face, rather than a smooth continuous pull. Its absolutely horrible.

1) Maybe a bad tune?
2) Plug or wire issue?
3) Exhaust leak...(pre muffler)?
4) Timing off?
5) Jacked up injector?

Any ideas or experience is much appreciated...we all know how shitty this feeling is.