Controller / Voltage etc Upgrade ?

[adamween]

I am looking at upgrade possibilities.

Current setup is
04 TXT PDS 36V w/ "Freedom Chip"
Rear seat, HD rear springs, no lift etc.
Just did a LIFEPO4 build - 36V 12S 230Ah (40.8V at full charge / rest)
1C continuous and 2C for 30sec supported
7-20S JBD 200A Continuous 300A peak (as wired thru the BMS)
1AWG Wires throughout. Maxes out at 21 MPH.

Curious about "budget friendly" performance upgrades.
Standalone 36V Controller SOL upgrade produce noticeable performance increase? (Ideal solution if it nets gains)
If so... Recommendations that wont break the bank..

36V to 48V require a motor swap or just extra VDC, SOL and Controller?
(This will require another 4 cells, $$$, and the additional work, and is not ideal.) Additionally, 48V LIFEPO4 would put the resting pack at 54.4V. Problems with that voltage?