The .21 XPE is no slouch of an engine. It is basically an Alpha Z852 with some minor changes (nothing that would really show performance wise). They're VERY tight engines from the start that require a rather lengthy break in period (easily a gallon), but they do last. Just don't go beating on it right away, it won't like that. I personally run P4s in mine, but I've been doing nitro long enough to tune stuff with my ears to know when it's right.

I've run my engine up against all the major brands. Just this past weekend against some of the NorthEast's fastest guys at the NorthEast Super Series, I TQed Pro Buggy and finished 2nd with my XPE. The track had a lot of high speed parts which this mill just loved.

It's a fantastic engine for the money that will run with some of the best stuff available.