I got a Suzuki X-90 for my kids (15-16 years old) . Here in sweden it is possible to rebuild a car to a "tractor". We call it "A-Traktor" There need to be done some things to make it legal for a kid to drive it. One of the things is to Make a speed limit to 30 Km/h. (10% margin is ok so 33 ) One thing we use to do is buy a RPM Regulator and cut the engine when it exceed a certain limit. And then lock out the 4 and 5 gear. This is not 100% legal but works. Now the question..
Is it possible just by reprogramming to limit the SPEED ? (not RPM) .. There is a VSS into the ECM.