2001 Yahama stock G19

[river_terror]

BAsed on what you guys have told me on how to increase speed, I've been checking around but am now more cofused than when I started. I found the following from Cartszone about controllers:
"New controller 400 amp for Yamaha G19. Will increase speeds to 20+ mph and torque. Easy installation just bolt and go. Water proof, Vibration Proof and corrosion resistant. 2 year manufacturers warranty. Works on 24, 36 ,48 volt carts. Drop in replacement comes programmed ready to go. Works with Stock motor" .
Will this really work to increase speed? They say more conroller amps increases speed and torque? Also talked to D&D and they said I need a motor and controller. Any help from the experts would be appreciated.