there is some intricate equation for horsepower vs weight equaling a certain quarter mile time.. but you have to remember, that's under perfect driving.. and also, that you're not always on the same horsepower because of peak power on powerband.

I think it was something like.. every 10 horsepower is a tenth off your quarter mile time... and every hundred pounds was another second.

I could be absolutely wrong, but give or take, it sounds right to me.