i`ve got a scooby sport back box and centre section with a hks down pipe fitted to my p1 and i thought that was all of the exhaust changed but have seen adverts for the up pipe.
where on the system is this fitted?

 

it's the bit before the turbo, but after the headers.

 

Theres no need to change your up pipe unless your going for big power-you havnt got a cat in your std one.