I have euro-spec MY06 WRX with Ecutek and 3inch Kakumei full decat exhaust producing 275 BHP / 490 Nm. It seems that Subaru has fitted speed limiter to 235 KPH that is usually reached at 6.000 RPM in 5th gear. Is there a possibility to remove this restriction as I think with another 500 RPM's available the car should exceed 250 KPH top speed?

 

Mapped into the ECU is a speed limiter strategy that backs off the throttle at 230kph. We leave it alone as we can't test above this speed very easily and I would suggest that it's there for a reason as the STi has a higher limit but it does have a bigger intercooler that may still work at high speed.

Whoever recalibrated your ECU will be able to alter it but without testing I would suggest that it would be unwise to do so.

Mike