Ok the ms3x is about 1000 bucks cheaper what is it missing from the proefi?
Features:
(Based on full featured MS3+MS3X+V3.57) Speed-density,alpha-n or MAF for fuelling calculations 16x16 fuel tables in 0.1% steps with true interpolation and movable rows/columns 16x16 spark tables in 0.1 degree steps with true interpolation and movable rows/columns Wall-wetting transient fuel control for better driveability On board datalogging to SDcard (max333Hz sample rate) Tuning by serial or built-in USB-serial port. 8 channels sequential fuel (hi-z injectors or low-z with external resistors) 2 additional fuel channels (hi-z or low-z) 8 channels sequential spark (logic level output) 6 channels mid current output for small solenoids or relays 2 'spare' conditioned 0-5V analogue inputs (+2 more raw) Two wideband oxygen sensor input (external controller required) (Up to eight widebands supported via external data capture) GM-style stepper idle control 2 and 3 wire PWM idle control Closed loop idle control Closed loop mixture control - ideally with wideband Closed loop boost control Various boost control systems (gear,time,speed based) Two stage variable nitrous control 2 step type launch control CAN communications to interconnect other Megasquirt products e.g. transmission controller Supports external data capture boards (e.g. for external EGT boards) EGT data support (with external amplifier) Staged injection Dual fuel (e.g. LPG) Table switching,(mainly for dual fuel use) Water/Meth injection Individual cylinder injector trim Injector phase timing Individual cylinder spark trim Support for numerous OEM trigger wheel patterns. Magnetic (VR),Hall,Opto crank sensor input Magnetic (VR),Hall,Opto cam sensor input