[lude1sh]

If my 99SH gained 15-20miles per full gas tank (91+ octane of course), does that mean there is more power, especially in the 0-60mph or 1/4 mile department?

This is true I gained about 15-20 miles per gas tank just by doing some lite modding.

 

[lOOkatme]

you probably gained more power since its easier for the engine to do work....IE probably breathing better through an intake or exhaust.......so PROBABLY you are going a little faster......but its not a definite YES that you are going any faster