i put a header on my friends gs and it gave a good increce in hp he loves it

 

The gains you will see are on a case-by-case basis. If the stock manifolds on your vehicle are efficient, you are not going to see much. On the other hand, if you have an engine where the exhaust manifold was designed around saving space in the engine comparment you stand to see pretty good gains.

 

mitsus manifolds are really not that great... not many stock manis are. either way there is some gains to be made out of header(s) and on the 3G eclipses I know they can help for a slight gain

 

where would you all suggest ordering headers from??? any specific brands?