I guess the basic answer is that yes, the stock s2 cast-iron manifolds are not very good.

You can indeed improve horsepower, by installing later s4 manifolds, or headers...

But unless you are going to redo the exhaust overall, there is not much point
in adding headers to a stock exhaust system. Why spend the time and money,
if you are only going to improve one part of the overall system... If the rest of
the cats, mufflers, etc, are restrictive, then headers will not give you as much
benefit...

 

Imo000,

You are correct - didn't look very hard at 'em and sometimes the S3-S4 line gets blurry for me - I've moved too many pieces around on those cars. I stand corrected.

Greg

 

Ok well in that case whos the guy that races and says all he has is headers? (im sure exhaust too)