I've gone on a motor binge the last couple of months where I bought tuned and dynoed at least 8 Monster Pro's, 2 Epic B2 Pro's and one Phantom tuned Monster. I use an Orion dyno to gauge the motors before and after my tuning steps. For tuning, I lightly polish the arm pins, cut the comm, replace the brushes with Reedy 767's (1mm shaved tips, no soaking), oil the bushings with Trinity bearing oil (before each run), replace the springs with Trinity purple springs on pos and neg (used with 2 teeth larger pinion gearing than normal, 26/96/48p) and use a drop of Trinity comm drops (actually increases spinup and top rpm by 200.
In my testing, the Monster and Epic Pro motors performance out of the box varied, and my tuning increased each one's spinup greatly with a slight drop in rpm. The higher torque allowed me to use taller gearing which resulted in a lot more grunt and the same or a little more top speed on the track. After playing with switching arms between cans, my second and third fastest motor in both rpm and on track acceleration came from Monster Pro's where I replaced the arms with an Epic Pro stock arm's that I bought separately and an Epic Pro stock arm from one of the B2's. I didn't replace them for testing, but because I wore out the comm's on both when first learning how to use a comm cutter in the early stages.
I felt kinda like Newton with a bump on my head after I dynoed them and saw the increase.
My fastest motor is the Phantom tuned Monster Pro. Out of the box it pulled 100 more rpm than the other two "tuned" motors and after shaving the brushes, using bearing oil and comm drops, and using both purple springs it increased another 200 rpm. On the track last week it gave me more acceleration than the local fast guys here and a maybe a little more top speed. I used one tooth smaller pinion than on the other Monster Pro's (25/96/48p).
The Epic Pro's were both slightly slower than the Monster Pro's on the dyno and one fried on me on the track. Won't go there again, except maybe for an arm or two.
With all that said, I'm going to get two more Phantom's and see if they are consistently better. If so, you know who gets my vote.
Anyone else have experience testing other stock motors and tuning steps side by side?