Going with a 4600 would give better runtime than the other motor choices.
I'd go with the 4600 if you aren't racing. And even if you are racing.....
A buddy I race with has a 5700 in a T4 and has it turned down to 60% in an attempt to make it easier to drive. I've driven it and there's still has plenty of top speed and acceleration.
Another guy I race (very experienced racer) with put a 7700 in a 4wd XXX-4 buggy. He said it is way too much motor. It was crazy.
Just another opinion. It's worth what you paid for it......
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