24.8mm is a little high in my opinion for a 8 turn on a 40 meter straight (depends what the turn before the straight is like...), I have never had much to do with flat wire stuff but I know they are supposed to be pretty rippy acceleration wise. I'd say go back to 23mm or so and give that a try. Without knowing more detail about the track (layout i.e., technical, flowing, high grip/low grip etc.) itís hard to give any reasonable suggestions.
The comm turning silver is bad, I would look at running some different brushes and springs, timing it differently (depends on what batteries you run) and then play with ESC settings and see if you can get better wear out of that.
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Mugen MTX & MRX
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