My clocked 25XZ ran flawless today. 1st full raceday with it. Ran 10 minute race without pitting. Great truggy engine! Even when track got real greasy late in the day i was able to tip toe around the track with it, lol. It's definately like a really stout .21, not like a .28. I believe it revs just as high or higher than my clocked B5.