I just purchased a stock ITR muffler that I want to mate up to a Medallion (Tanabe) B pipe. I noticed that the stock ITR muffler uses a donut gasket and the Medallion uses a flat gasket. I'm sure the proper thing to do is cut and weld the proper flange type, but can you get away with using a flat gasket with the donut flange on the muffler?

*EDIT* I don't think this will work because the Medallion has the hanger near the flange of the muffler whereas the OEM B Pipe has the hanger on it. If I were able to get the flange to work I would be hanging the exhaust with one less hanger.

 

Most aftermarket exhausts use that flat flange with a thin gasket, whereas OEM exhausts will use the donut gasket with spring bolts. In order to get your setup to work you'd really need to bring it to an exhaust shop and have them cut your b-pipe and weld on an OEM flange.

Another option would be to buy an OEM or oem-replacement B-pipe and sell the aftermarket one you have.

 

I'm trying to source a USDM ITR replacement B pipe, but they are not easy to find. I have seen OE replacement B pipes for LS and GS 2 doors, but it doesn't say for GSR or Type R. Are there fitment differences?

 

Ah... truthfully I have nothing to share for best aftermarket replacement options at this time. The difference other than piping diameter may be the catalytic converter length. I know there were subtle differences between GSR and LS/GS/RS cars. Not sure how they stack up against in length with the ITR setup.