I know what you mean. I pushed mine down and watched it rise too. It should've made me miss a gear too.
I have had ZERO problems from the tranny. No vibes as previously stated. I am not sure, but I think the tranny are different from early to late 01, same for Gt's. The later cars have tremec 3650's which is much stronger than the t45. Only real issue I have is with wheelhop. I have 450rwhp and have snapped a axle due to wheelhop on street tires on the street. Other than that I love it. Now, it is still a Ford, so expect the typical fit and finish and some rattles. I work for Honda so I the rattles annoy me. But thats why you put loud exhaust on a stang.