Unless that improvment is not just the X-pipe,a big part of that improvment might just be due to a complete swap from a restrictive stock exhaust to a complete highperformance exhaust from the stock manifolds with an X
You probably wont see the same kind of improvment on a car with a complete mandrelbent 2½" exhaust with good mufflers on a car with headers if you just add that X.
That post is an intresting piece of information,just not sure how to use that piece of information without knowing more.
Just trying to put things into perspective here so we dont make people think that all 300hp cars will improve there quartermile performance by a certain amount from just installing an X-pipe.
Oh i just realized i read the post wrong .3tenth is a very small gain i thought it was .3seconds. every gain is a gain but that was a rather small one.