as mentioned above, Perhaps the wastegate is stuck open, This could be from a stuffed actuator, or as ruby said, maybe the wastegate is stuck open from the exhaust change somehow. Does it show any boost on the guage at all?
If anyone knows a little fag kentn in a Non turbo 32 with no spoiler who hangs around the western suburbs tell him to slow the f**k down, he knows who i am because i just followed him back to his gf's house and abused the f**k outta him, pretty sure he wont do it again but the streets aren't a f*kkn race track you twerp.