The .18TZ is alot more powerful. The TRX 3.3 puts out .92 bhp. The OS .18 CVR puts out 1.35 bhp and the OS .18 TZ puts out 1.8 bhp. In the Jato the TZ is a screamer. Im actually getting one from my lhs for about 225.00 which is alot cheaper than the other engine I was thinking of getting for my Jato.