rustler gearing help, please.

[schofield]

heres the specks: 16/90 VXL, 7 cell 4600 badlands all around. my motor is hitting over 160 and over, near the 3/4 through a pack. (i usually stop driving if i hit 160 or so, don't have money to through away, i get a RC allowance from my wife and thats it.)
mostly dirt road driving, not hard on the throttle or brakes, some grass, but its just driving out of it after jumping into it, its cut short. could i be under geared and the motor is not running efficiently? or the tires have to much hook? any suggestions? you saw this before but heres the vehicle.


the star on front is for weight and to leave a star imprint when i smack something.