I've been researching swaps for a while, and I still have a couple of questions regarding swapping a 2001 usdm b20 into a 96 civic ex: 1) If I use a 99-00 si header or aftermarket equivalent, will it fit with the 1996 ex cat without modification? I was thinking length should fit, but maybe the flange would be different. 2) If I use a hydro gsr tranny, does the clutch I get need to match the b20 engine or gsr tranny? I take it the b20 and b18b are similar, so could you also get the clutch to be compatible with the b18b? thanks guys.