08 perrin downpipe fitment

so i just bought a 08 wrx perrin downpipe for and when i called perrin they said it will fit i just need to cut the diverter. anyone know how i should go about doing this?

You could just use a cutting wheel on a dremel and cut it. If it has a cat in it put a rag so no metal shavings fall into it. You don't have to cut the whole thing out either just till its flush with the flange.