Charles for the win. The race car is light as a feather and there a rules that keep it around 450-500 anyway. A little bird told me they are using the stock cylinders at least with the Cosworth perhaps also the Mahle. Keep in mind they do something like 25 laps and they run on the very edge of rich and so every once in a while fire comes out. Sometimes they get fire spitting out of the side many times per lap. It is not lean like a guy with a bad tune plus then also NOS (not good idea at all for these OIO cylinders Do I want sleeves like Charles yes, do I have them no