Chally77,
By far the best bang is to put in an SRT8 Challenger suspension. They can be found here on a regular basis for 350-400 or for about 100.00 more you can get the suspension from moparsupercenter.com Thats springs, rear shocks, and front struts.
This a high performance Bilstein setup. I'll say it again by far the best mod on the car except maybe for my CMR Diablo tune.
FYI,
Marion