Basically man... you just gotta find some springs from another MFG that are about the same length and diameter as the WR8 ones and are stiffer. Losi, Associated, Traxxas are just to name a few. If you have a decent Local Hobby Shop you could just pop in and check all kinds of springs out. Hope you find what you are looking for.
Wade Huesman, TCORC Secretary/Pencil Pusher