Will first it has to do with the T Max! I know you need to buy all the RPM parts you can for it if it does not have them all ready if you what to drive it much or for long. The engines are like the T15 some are good and some are not so good more so with the 2.5 then the 3.3. Personally the only Traxxas I would consider would be the Revo only if they made it in a kit with out the radio and engine. I am not bashing I am stating my opinion for those that need to know.