+1 with TG the xl pistons work well, & will give you higher comp which standard replacement units wont of course - the Davies parts are impressive but I wouldn't put ultra trick pistons at the top of the wish list on these engines, there are better areas to spend your money, especially if this is an initial build. My advice, take a look at some of the excellent build threads on here by guys who are racing these engines, better still, spend time talking with folks in the paddock, you can get more gems of reliable info in a 10 minute track-side chat than hours of trawling the net & the after-market websites.