I'll soon be replacing by pathetic d15y6 with a less pathetic b18a1 in the very near future. One thing I'm unsure of is the exhaust situation. Will the exhaust mani from teh b18 bolt right up or will there be a gap? If so, is there a custom cat i could buy to fit the gap? It's something I'll be replacing anyway so I thought I'd ask.

 

i think the b18a1 exhaust manifold is longer. cut the flange off if it is and weld it back on a couple inches shorter.