Oh yeah, I forgot about that!

I used some advice from the Red Ranger staff. I stuck the bushes in the frezzer overnight then quickly transfered them to the vice and drill them using a wood/blade drill bit. Took a couple goes to get the size right. I think the bit had to be about 2-3mm oversize to get the correct hole size.

Not hard. If I did it again I could modifiy all the bushes in about 30 mins. Simple stuff really.