Originally Posted by Pro10noob

Depends on what track your driving.
As for the Xray FDR i think it's a short tech track.
If that FDR is ok then you can use it on the E4RS 2
With a 110 spur and a 41 pinion u get a FDR of 5.52.
If you go with a higher pinion your FDR will be lower.
If you go for 48dp spur you can use the 80 spur gear and a 31 pinion and then you get 5.49 FDR.
It all depends on what track you drive on.
I my self drive with a FDR between 4.24 and 4.36 but that depends on what motor i use.

cheers Roy