I think what KYSol was talking about was where they tested the tornado and things like that, the magazine might have had more stuff in it though. In general everything about a car is tuned to the worst case scenario, Also things like intake & exhaust are designed to reduce noise as much as possible. while a few HP per mod might not be significant, doing 4 or 5 things that add a few HP each can add up.

Here's the artile I think KYSol was refering to.
http://www.popularmechanics.com/auto...y/1802932.html