I've seen some posts where people have increased their spring rate in the rear by using 64-66 mustang springs. The only info I've found though are people using fixed rate springs. I was wondering if anyone has run progressive rate springs.

I found some C5ZZ-5310-PR they're pretty stiff at 620lbs but with the progressive rate I'm hoping that dampens things out a bit. Since my primary intent with mine is carrying things, I think a bit more oomph in the back end would be a good thing.