depends...Duckys V6 runs 16.5s with a nelson tune, vette servo, heads, exhaust etc and stock rims.....That guy on PT probably had more mods on his than just stock and 20s....Cause Mine was stock for a while with 20s and it was freaking sloooooowww....and plus I just looked on Hypertechs website and the HP gains were only 5-6 HP