Don---I tried a double return spring system on the RPU. What I found was that when leaving a dead stop, the car either didn't want to go at all, or else wanted to go like stink, all of a sudden. After laying about 8 foot of rubber when coming off a red light, right beside a local officer in his cruiser downtown one day on hot pavement, I slunk home with ears burning, and went back to a single spring system.---Brian