2003 CC Pathway Speed controller upgrade

[enriched]

Hi. New to the forum.
Have a 2003 Pathway. Top speed as of now is 17mph with a new speed sensor, batteries, cables, MCOR, and "high speed" magnet. Has a 250 amp speed controller...thinking of changing it to a 500 amp controller, (do I need to change anything else? Solenoid? motor?). Can I just change the speed setting in the OBC with a Code 5 Programmer? I am assuming the motor can take it. The rumor is these were de-tuned before being sold to the public?? Also adding a back seat that ways 90lbs, (had to remove the roll bar to get the seat in so maybe only adding approx. 50lbs). Needs to do 20+ so I can register it. Any advice is appreciated.