Thanks, that's worth knowing! I assume you drilled by hand, ie with a twist brace??

 

No, I just went with a normal electric drill. I couldn't go directly straight in because the suspension mount was in the way.

 

I had the same fault, cured it by using Revive Turbo Cleaner, car runs like a dream now!
No need to drill and Mr Muscle!
It costs £34

 

The only issue there is that you'd have to splash out £30 every time it clogs up, but I suppose a bit of preventive maintenance, like a cheap off the shelf fuel additive like Dipetane or Redex every few months, might keep it clean. And I suppose that would sort out the whole system, not just the turbo vanes.
Tapping the hole really isn't that big a job though, once you have the tools, but it did take me a few weeks to build up the courage to do it!
And I think I just ended up doing it just because it seemed like something fun, dangerous, and a bit interesting.