This engine (Toki .27) seemed to get pretty good reviews. My GF has the .21 version in her Mayhem and it really is pretty good, especially fo a $74 engine. It pefoms about like a better-than-average stock .21 engine. So I think the .27 version would do even better especially for a basher.
http://cgi.ebay.com/NIB-Infinity-Mon...742.m153.l1262