Im interested to see how this works out for you. When I bought my system, I spent quite a bit of time talking to Bill. He typically recommended the 450lb in front, but since i had the viper motor and intended to autocross, we stepped up to 550lb (btw sway bar is 1.25").

Bill did say he would do a free swap with me once if I wanted a different spring rate.

On the car, it feels quite stiff - but car isnt fully assembled or driveable (mock up), so I cant give you a real world testimony for a while.

My car is lowered, and I have found that springs supplied are too short under full rebound - so I'll need to adjust accordingly down the road. Just something to consider that if you intend to run a lot lower...