Do any of you use springs other than the stock CEN springs on your Matrix buggy?
I find them to be a little too stiff for my track.

Thats crazy that you posted that about Matrix springs. I was going to post a similar thread asking about Matrix springs, and shocks. I however am looking for stiffer springs. I feel like the stock springs are too soft and the shocks in general offer way too much droop. My Matrix bottomed out bad the first time I brought it to the track. I replaced the stock shock oil with 50 weight. Not much better. Smoother but it still didnt seem to offer the feel I am looking for. I am also looking for stiffer springs and I plan on stepping to 70 or even 90 weight shock oil this weekend! Good luck!