Toddy - it depends on your build mate. I'm fairly lean and have a skinny ass. My mate's a Doc here in the UK and he was aghast when I told him I was using 1.5 inch pins for my glutes. He told me to switch to 1 inchers and said that he didn't know anyone at his hopsital who'd use a 1.5 incher. Then again, if you've got an ass like a house end.....