I have an 08 XTX
I rewired it 2004 style and replaced ECU also.
Bike now runs much better.
So, I think, in theory, your 04 bike will run smoother than the 07 model..
I don't know how the other year bikes compare but my 08 didn't run so well before ECU swap. LambdaBolx

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PCV REPLACEMENT ECU WITH 04 WIRING LOOM STAGE1&2DNA GEL SEAT INSERT LOWERED 20mm FRONT+REAR CLUTCH ARM MOD
FORKSPRING SPACERS TALLER SCREEN THROTTLE GRIP CAM MOD DISTANZIAS 46TOOTH REAR SPRKT
SPEEDO HEALER 30MM HANDLEBAR RISERS TOPBOX MOUNT 08 XTX SORTED, ALMOST.
...SHEEPSKIN - Because a pain at the rear is not just a moany pillion.