Associated B44 & Caster S10b lacking punch?

[Sumilidon]

Hello all,

I may be missing something here so any advice would be appreciated.

The B44 parts have finally appeared in the post and it is now built and ready to go - however when I push the throttle forward, they both (including the caster) seem not to lurch forward as powerfully as I have seen other cars - as if the Diffs are undergoing too much force and are spinning internally. There is no wheel spin.

As such, I'm not sure if this means the diffs (or slipper) are too loose - or just knackered.

The B44 also pulls to the right initially on full punch, as well as the pinion and spur not seeming to be ideally matched on the B44, part of the rotation is smooth, part is noisy.

Technical info:
B44
13.5T brushless motor, 35a ESC

S10b
8.5T brushless motor, 60a ESC

Any help, suggestions or links to guides to sort this kind of this would be appreciated