OEM, STI Genome, Apexi World Sport2:
This is why the Genome caused an instant power drop (also raised engine temps by 10 degrees), bottle neck at the flange taking internal diameter down to 42mm. OEM pipe is straight 52mm internal, Apexi WS2 is 58mm. My midpipe is 58mm.
Apexi left, Genome right:
I need to massage the Apexi mounts to get it to sit straight and stop knocking, but it sticks out past the bumper by 15mm, the Genome was 15mm short. The Apexi is the same tip width, but it\'s slightly oval, so sits higher and fits the bumper better (or will once brackets are fixed):
Edit: Ive tried bending the muffler brackets but I\'m going to break a weld, so it\'s come off and back to the little OEM for now. Going from Genome to Apexi I got power back and block was 10 degrees cooler.
Thanks for info - noted for future ref! I have a Fujitsubo turbo-back with (equal-ish) headers , but a factory up-pipe (dunno why they didnt just shell out and replace that too!) wondering what kinda internal restrictions I may have hidden under the heat wrap....