Hobbyzone Mini Mauler, right? I own one too...
Well, it comes with a 180 sized motor by default with a rear bulkhead and motor mount that will not accomodate anything other than a semi flatcan 180 motor. HobbyZone have their own "performance motor" for the Mauler, I have no idea how fast it is though.
Another option is running 6.0V packs, I made my own custom 5 cell 2/3AA pack for the Mauler and it flies along nicely.
Other than those options the Mauler is quite limited on hop ups. It is more of a toy than a competative Micro and handles like jelly on the San Andreas faultline.. but it is a lot of fun!