If it's just a case of getting a hole between the inlet and outlet, then I'm going to go mental with my new makita. I don't have much to lose, it's broken anyway. If it does work, it saves me spending £100 on a new housing, and will cost about £25 instead.
I'll report back once I've broken something.
If it's a success, I'll buy a Mahle filter that Triumph use, £16 on ebay.