It is possible to increase performance of the older RWD, although there is a fuse harness that would need upgrading and you would have to increase amps somehow. To me Tesla decided not to increase performance as it would probably stress the rear motor and create more heat making their product unreliable. The dual motor 75d had the capability as it's the same basic drive train as the 90d. My guess is after your warranty runs out, there will be an after market performance upgrade for all the older cars