it definately hurt. that is all mass that isn't doing you any good. i woudl bet that each front wheel+tire weighs over 65lbs, now look at a pair of draglites with bias ply skinnies, around 15lbs each.
unsprung weight like a wheel also isn't doin any work to help the car hook. it doesn't move, it jsut drags on the ground and fights the car.
the narrower tire means that less rubber is hitting the road, less tire on the ground means less rubber that is resisting acceleration.
i know when i switched from 17's to skinnies on my thirdgen i knocked a little over a tenth off. that was with M/T 8ply(my car was still full weight
) fronts though, with a 2 or 4 ply front it would have been even lighter and i would have knocked off more.
later
tim