One of my friends is running a Stillen SC on his 2003 full blown, caged, space framed race car. He purchased the car brand new, drove straight down the road to get it caged. It's a race car only, it gets thoroughly abused, driven at full belt the whole time doing Targa and other events, so spends most of it's time up around 200kms +++++, being driven as a race car should. After 20k of total racing abuse at events, he managed to kill the SC.
I think that's a good testament to the quality of the SC products, given it's a racecar and never ever sees sedate driving.
One of the other guys here is running the Vortech SC, it sounds alright on the track, I don't know too much about the car though, as he's a fairly quiet member.