Mine has a 3" TBE with decat to a non resonated Milltek cat back. At idle and cruising speeds it is virtually the same as stock but when you open it up it makes an insane noise. From the outside I've been told it was as loud as a Focus RS mk2 that I may or may not have been having a play with. lol
I'm guessing yours is a DSG to explain your noises when changing gear (dsg fart lol). Your mpg will probably drop horrifically now as you'll always crave the noise, especially when you've first had it fitted.
I'm from Birmingham.