I went to the RaceTech site and checked on springs. I guessed at your all up weight and put 310. At that weight they recomended their heaviest springs front and rear. Springs at either end are $114. Hope that doesn't blow your budget, you will be better off with the springs.
Other sourses are Cogent dynamics and Ricor and Progressive Suspension. Google away.
RR's Catnip Hill to Peoria ___Loopin' Seattle to WestFest
It started with some beers __1500 miles to the Dentist
Skeedaddle to Seattle______ A 30 year old on a Three Flags Run