Nic, although I'm happy to get an Invidia Gemini exhaust for you, before you spend anymore money, try the following:
- check fitment issues - vibration under load makes the pipes touch body parts under the car, check heat shields, usually the bolts on them snap very easily.
- if that doesn't solve it, try welding brackets on the Invidia test pipes and fit the OEM cats brace on them, that should eliminate the rasp.