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not exactly the same apparantly the gt4 has diff part number for: turbo charger engine ECU (obviously, although the connector pin-out is almost identical. Probably the same PCB programmed with different software and with perhaps some components left unpopulated). complete engine assembly (ST205 is 1...

if you have induction and zorst i would also gut the tvis and grind out some grooves were the butterflys were you loose a big of low end but mid/high is alot better as the air velocity islower helping higher revs then i would advance a bit of timiing

hi,
you might check the tvis operation to make sure the butterflys are not stuck open this will limit low low down torque due to decreased air velocity.Also tr advancing the timing for a bit more torque throughout the range retarding generally looses power