How long do you think 1 added spring will last while racing?Not to long with hard launches I bet,tires are expensive.This may work on a street car as a band-aid til you could afford new ones.My 2 cents.
How long do i think it will last??? well considering that there are many who run totally stock suspension, as in stock 6cl springs, torsion bars, shocks etc. and run much faster that i or you have ran for that matter, im pretty sure they are fine...why dont you go and tell all the guys who run like that that they have "band aids" and "tires are expensive"...your rationale makes no sense whatsoever...guys who believe that it has to be all pretty and new to work make me laugh, especially when they lose to the guy in the lane over with stock stuff
ill give you an example on just this site...tenseclegend's 9 second footbrake dart runs all stock 6cyl suspension...i can bet there are more on here like that, and theres many more on moparts...thats just a start...but whada they know, right?