I have a couple of fitment issues with the SR Motorsports resonated midpipe I installed recently, and if anyone has been through any of these problems with their midpipe and has any suggestions or tips I would appreciate hearing about your experience.

A little background: running a SR Motorsports downpipe & RB cat-back, installed new OEM motor mounts last summer (less than 1K miles on them), stock cat fits perfectly. I install the midpipe and everything seems fine except the rear flange isn't aligning with the flange on the cat-back. I'm anxious to get the car running, so I throw a second gasket in to help minimize the gap as a temporary solution:



Car starts up and idles with no issues for 30 minutes while the PowerFC re-learns the idle. I go for a test drive and within 10 minutes I can hear the pipe clunking against something under the car, and as the exhaust gets hotter it starts to make constant contact with something and the whole car reverberates under throttle. Back under the car, when I move the midpipe around I can tell it's making contact with the bolt heads from the trans tunnel brace:



I pull the pipe back off, and sure enough there are two marks where the bolts have been hitting the pipe (and a third contact point with the heat shield, but that's easy enough to bend out of the way):



At this point I also decide to compare the midpipe with the stock cat to make sure the mounting points match up, and sure enough the midpipe is 2-3" longer and the rear flange is not aligning at the same angle:





I'm going to try to find some different bolts with a lower profile head for the trans tunnel brace to try and gain some additional clearance, and I also thought about trying to "dent" (for lack of a better term) the midpipe where it's making contact but I'm worried about damaging the pipe. I was also thinking about going to a machine shop to have the rear flange ground at a slight angle to get it to align with the cat-back flange, or maybe try it myself first with a drill & grinding wheel.

Any feedback, input or suggestions would be greatly appreciated.

 

This looks like a used MP, is this correct? If so, are there any wear places on it where the previous owner experienced the same issues? Mostly with contacting the trans brace bolts? If not, something seems aligned wrong. Or possibly the new motor mounts raise the motor just a tad higher than stock causing the bolt contact. As far as the catback flange, I would have a shop grind it like you thought only if it will leave sufficient flange material not to warp under heat. If they question that I would just have them cut the flange off and reweld it in a better orientation. This is all I can think of off the top of my head...