hello, ive just got some R.O solid alloy handle bars, upon fitting them i noticed that they dont have the hole for the positioning of the throttle housing, obviously im gonna have to drill the holes but has any one got any tips for gettin the holes in the correct place? is it just a case of using a tape and getting it near as?

CENTRE PUNCH.

Most importantly, drill down into the middle. If you are off, the throttle will move. ISSTR the hole is 4.5mm? If I am right, don't be tempted to use 5mm, it will leave the throttle loose. Can the billet bars be turned round? Be sure the brake lever won't catch the throttle cables.

That's about it yes. A bit of insulating tape will stop your drill bit slipping.