I just recently swapped my ls engine for a b20 motor w/ the ls tranny and everything runs great and it's very nice. a friend of mine gave me a header and downpipe from his ls motor. from a b series to another b series, i'd assume everything should fit perfectly.. but when i installed the header, i noticed that the engine became remarkably loud. With the car running, all along the bottom of the header, there is a huge exhaust leak. you can feel all that hot exhaust fumes flow right out with your hand below the bottom of the upper part of the header. the gasket that came with it totally dissappeared on the bottom, yet it was a cheap gasket that appeared as aluminum foil w/ inner cardboard. i replaced it with a stock, metal gasket and it quieted down a lot, but yet there is still a leak along the bottom. is the header just a crappy header, or is the header even the right size? If not, what header would be a best fit? I read up on Pro-1 and people seem to find that header on the b20's very nice.

any ideas?

thanks

 

tighten the bolts to compensate on that side or ue some exhaust cement or some exhaust foil tape, if its a small leak it will fill itself with carbon and shut the hell up

I use exhaust cement on every joint, cheap, effective and easy