and now my exhuast is rattling, i noticed that my muffler is about 1/4 inch out further than before. I had to push out on my catback to get the cat between the header and the be pipe. It only rattles at idle and rpms. Im assuming the catback is rubbing against the metal parts of underneath the car, what can i do? get underneath and jiggle around and try to get them to seat in the rubber hanger? or take it to a shop and have them look at it?

JDM 4-1, carsound cat, Apexi N1

TIA

 

DId you remove the heat shield above the cat?

 

yeah.

 

I had the same problem when I installed some POS DC 4-2-1, seams the header pushed the whole system back about an inch and a half, enough where the pipes were rattling against the heatsheilds.

I took it to a muffler shop and had them cut out a small section of the A pipe, and weld it back together.

 

I assume you have a GSR? The JDM headers, stock and aftermarket are longer than the regular GSR header and cat combinations. When I put my Mugen header and cat on I had to have my GSR Greddy PE exhaust shortened or it would not fit properly. You may have the same problem...

 

although its my o2 sensor thats hitting the shift linkage, someone suggeted bending the hangers on the exhaust piping, I have an apexi exhaust too.

 

Don't bend anything, go to a mufflershop and let them cut a small section out of the B-pipe and everything will fit like stock. I'd guess that you'd be out no more than 20 bucks.