when i swapped over my d15b i used my si exhaust manifold, long story short im trying to swap over the manifolds now, so a buddy of mine has a da and he just got a header and downpipe so he gave me his downpipe, so everything bolts up except the catylitic converter the flanges are positioned different so i cant bolt it up.so what have you guys done that have swapped motors that want to go to the 4-2 design exhaust manifold? any suggestions thanks

 

i ran into the same thing with the flanges being clocked differently.....

i went from an aftermarket dcsports header on my d-series, to a stock header on b-series.....

anyway, each one ended up being the exact same length to fit the same exhaust. the da downpipe was such a tight fit that i just had to angle them both down (unbolted) then push them together in place - kinda like snapping into a slim jim by pushing up lol - and then the header bolted in place. the header & exhaust STILL aren't bolted together but they're snug enough to stay.