HV 4.5 you mean you're running? I tried an HV4400 in my Rustler (before the sintered rotor and stuff). That thing HAULED on 12 cells..... Ran a little hot at around 150F for what it was though. I think I ran 23/86 with that motor on 12 cells. Tons of power, but very very smooth. I still have the setup too, but the ESC is fried (engineering side of me got inside the case............hehe).

I just ran 21/87 with Mashers now, and the motor is handling it fine. Around 110F off a run doing some off road and on road action. Good stuff....