Holding revs after boost
 

Hi, I am having a problem withmy 2003 sti type uk. I removed the Turbosmart bov that came on the car a fitted a second hand standard one. Since then the car seems to hold its revs on gearchanges or when coasting with the clutch in. However it only does this if I have been in boost. If I stay off boost it is fine.

I have since fitted the Turbosmart BOV and the car is fine again.

Could the standard BOV be faulty?

Thanks in advance for you help.