Yeah - on opposed twins the governer link is located under the carb . Unless the motor is prepped to run w/o one , i wouldnt remove it. Beside over revving the motor, the flywheel/motor can explode.
Twins have more then enough power even using the governer - i propelled my 18HP opposed twin murray up to 40mph using the governer ( I probably wouldve gone faster if it handled better - was a serious handful to drive at high speeds) - trick was to use a hand or foot pedal that snapped back as soon as the gas was let off - gave crisper throttle response, more power.
Another way for more power is to adapt a motorcycle carb or snowmobile carb along with a KN high flow air filter.
My murray was a shift on the go type trans , meaning no clutching while upshifting, and faster shifts - i ran a 6" motor pulley and 4" trans pulley along with 4 8" rims , tapered bering front hubs - slightly larger wheels will give some more speed, but itll get some lag when taking off.
I mentioned the steering was horrible for a basically stock tractor , along with pretty much non functional brakes - a combo not good for 30plus MPH..... its reincarnation will be built for those speeds .
A future build is a super mod, using an 18HP twin, either a RAGB ( right angle gear box) or 700 peerless , straight axle , lowered to the hilt .