It holds a tune well, is fairly fast, and is very similar to the Dynamite mach .21, the SH, LRP or Nosram engines (all made by golden Lion).
Its a league below the others but if you look at my post above and get one at that price its well worth it, if your gonna pay $189 your a fool for not picking the mamba or Go-tech.
At $100 ish its a steal, and one of the better 'budget' engines.