Put a traxxas 3.3 in it. Best and most reliable engine. Run great in the cold too with just a sock on the heatsink. Those 4.6 motors are horrible in the cold. I had a picco .28 (by ofna) in a truck and it had tons of power, but was the worst engine ive ever had. The 3.3 seems small, but it rips, i love it! Got 3 of em at the moment and there great, wheelies, 65mph+, easy starting (sits all winter with proper storage, primed good, and fires up right away!) Easy to tune etc etc! The list goes on and on how much i love these little motors. The 2.5R is alittle less powerful, but absolutely indestructible and even easier to tune etc etc!!!! The 2.5, stay away from it, not so good, runs pretty good in the cold cause it keeps the temps but i have had one blow up on me lol. But yeah, throw a 3.3 in it and it will be more then happy. If the chassis will allow it.