Crt.5
 

I was looking at buying a CRT.5 and wanted your guys opinion. I have a 7XL Feiago motor and was wondering if that would be ok with a mamba max and a 3 cell lipo? or would i be better off using the 5700k motor with the mamba max esc...

The XL motors really are too big/heavy to use in the small CRT.5. Keep in mind that many people use them in vehicles twice the size and twice the weight of the CRT.5.
Some have concluded that the Castle CM-36 motors are too small/not powerful enough for the CRT.5, although I haven't tried for myself.

I have had excellent luck with a Feigao 540C 9L. It never gets above 145 deg. F, and is geared to push my truck to 45+mph on 3s 4000mah 20C Lipo. In terms of physical size, this motor is still big/heavy. If you can afford it, a Neu 1509 series motor would be better suited.