I recently installed an S5 J-spec engine into my 1991 vert. I was unable to use the stock N/A cat cuz its way too big. I have about 12"-14" between where the j-spec downpipe ends and the rest of the exhaust begins.

Does anyone know if a stock cat from a US TII will fit in that hole? or should i just get a universal cat and weld on some flanges to fit into the space? If I can save my self the trouble of milling out the flanges and fitting and welding it up so it fits into the space, I would gladly buy the stock cat.