Drilling frame for internal dropper - yes or no?

dirkpitt74

So I've picked up a short dropper post for my lads bike - only snag is that it's internal routed and the frame isn't - details guy sent of post were for external routed post.

I did think about routing through the BB and out of the drain hole - but it's a cartridge BB and haven't got enough clearance for the cable.

I've seen a few people have drilled frames but I'm not entirely sure about doing it - have seen the instructions that Liteville posted and read a few other threads. Seems to be a 50/50 split on round or Oval hole.

No warranty issues on frame as it's an old'ish Carrera frame.