i was wondering what is the heaviest gauge strings i could get away with on my RG321MH im sitting on 9s at the minute but would like heavier, but dont want to feck up the action, and i dont reall want to drop tunings lower than drop d to honest.

10s? You'll need to screw around with your guitar a little whenever you change guage though, frankly.
Feel free to ignore my ranting.

Member of the Self-Taught Club.

A recent study shows that 8% of teenagers listen to nothing but music with guitars in it. Put this in your sig if you're one of the 92% who isn't a close-minded moron.
I onced used Martin 13's on my acoustic which actually gave me a really good tone. It was harder to play, but well worth it because of the sound
I use elixir 13 acoustic string on my squier.

It almost makes up for the fact that it was completely dilapitated and unplayable when I got it.