Will the P1 back box fit a standard MY2000 turbo.If so will it sound better than standard?

There are 2 P1 backboxes. One has P1 on the side of the tail pipe and is a performance add on supplied via dealers and Prodrive for the P1.
The other is the standard item and is stamped STI on the side of the chrome tail pipe.

Both will fit.. both will improve things but sti one only very very slightly.. slightly deeper sound and looks nicer. I found my turbo spooled quicker but I suspect my old backbox was full of sh1te. worth no more than 50pounds.

P1 stamped one is freer flowing and louder.. pretty nice.. worth about 100 to 150 at a guess.

Rest of P1 exhaust is the same as your car.

JGM :)