Notchy motor
 

I've just put a brand spanking new 9.5t brushless lrp stock spec motor in my lazer zx-5, and I've noticed that the motor is very notchy. i.e, when the car slows down you can hear the motor notching.

Is this just because it's a new motor?

I don't think so, are your diffs adjusted correctly? That nasty notchy noise can be the diffs slipping which is not good. Check the pinion is meshed to the spur correctly too.;)