8XL Gearing

[XSKAPE]

Hi,

I am new to the forums.

I have purchased a E-maxx 3906 second hand.
The current set up is as follows

UE 8 Sypder Diff: 3.31
Standard Trans locked to 2nd gear 1.72
OFNA 51t spur
Strobe Slipper
2x 7.4v trakpower
BK 9920
Proline 40series Bow Tire 5.8"
Gorilla G3 chassis
8XL motor 2084Kv

I want to gear it to about 40mph

according to the R/C calcuations at
http://scriptasylum.com/rc_speed/_solver.html

It suggests I need to run a 21 or 22 pinion.

Would this cause any heat problems or any problems at all? thanks

Also I'm planing to run 5s in future.