So I've popped the 25 on and tried it out. It seems to work fine and is definitely a good bit faster now. I may try to step up a tooth or 2 as the esc was still cool, the motor was slightly warm but only slightly.
I have issues though as usual lol.
Firstly these grub screws are crap, I have managed to strip the one that's on now, so if I do step up it's gonna be a bitch to get off, any ideas?
Secondly, where it is mounted now, is as flush as the pinion can be to the spur and there is no more room at the screw mounting points to move it back at all, which worries me when moving to a larger pinion as I don't think there will be room. Would I be okay using a round file (I have one the same width) to file out the mounting holes where the screws go to be able to move it back more?
P.s. thanks for the pinion tip, glad it's got more speed now. Really want to find out how fast but I don't have an old phone to use, and I'm not strapping my s7 to it juuuust Incase lol