I've been told that NASCAR allows five year old SFI belts in their cup cars
I also heard that they got a lot stricter in their inspections on how their belts are mounted after Dale Earnhart died in his wreck
My S/P car sits in the trailer or in the shop out of the sunshine when it is not at the tracks, I race it a lot less up here than when I raced in SO CA so my belts are looking really good before having to replace them every two years
I've said for many years , if you have a cheap head buy and use a cheap helmet
AKA aside, buy and use the best ones you can get when it comes to buying and using all safety equipment