what 1515 1y or 2d for 6s

I have the 2.5d (1650KV) and that is where you want to be especially if you will be doing more off road running, if your rig will see more street action you could go with the 2d I think with the 1y, it is too much battery for that motor. It is not so much the performance of the motor but the whole drivetrain and if you have too much power your wheels will just spin and you will get no traction