Yea, if the car doesn’t spin, upgrading to most any other rear suspension isn’t gonna make the car’s incrementals any better.
I have actually seen guys go from 002/003 Mopar leafs to caltracs to supposedly improve 60 foot times and fight and chase hook trying to get them to duplicate what it was already doing previously.
Like the old saying goes, if it don’t stink, don’t stir it…lol