03GT5spd

ok so i have a 03 gt 5spd when i bought the car it already had a stage 2 clutch and a short thro i think it might have gears but im not certain compaired to my dads 89 5.0 it feels like it but i knoe they came with gears compared to the 5.0 i have put trick flow underdrive pulleys on it and have been happy with it so far but last time i raced my brother inlaws ws6 trans am at about 90-100 he creeped past me since then i got a diablo predator tuner but havent raced him yet so i just ordered yesterday trick flow 75mm throttle body trick flow elbow plenum also 75mm and a cold air intake k&N so my question is how much power will i gain from the new mods plus the tuner and will he still creep past me at higher speeds if so is that cause he is a lighter car and more power and taller gears ?

Obsequious1

This section is for issues related to the forum. Not tech Q's.
Check out the 4.6 tech section. My guess to your question would be to get it dyno tuned.