I've looked all over the internet and can't seem to find any information on the RUF lowering spring for the 996TT. I've found info for the H&R, TechArt, M030 and X74, but not the RUF. I understand that their info is proprietary but has no one ever found or measured that info?

I'm trying to get these springs approved for SCCA use since they're already on the car I'm buying and need to prove that, although more expensive they aren't better than the other ones available.