If the HKS TI for the STi is like the TI on any other car I have heard it on, it is very loud. Loud is not always good. There was a WRX the other day along side me in traffic, not sure what he had but his exhaust was loud and sounded like arse. That combined with the BOV made it sound real bad. It probably sounded good to him inside the car but on the outside it was terrible.