I have a small matalic grinding noice on start up for 3 sec, then it goes away.
Also when the car is cold, there is a loud noise (sounds like a vibrating one) then goes away when it heats up. But this is only in drive, in parking there is no noise when the car is cold apart from the grinding noise for 3 seconds

i've been told it the exhaust flexi and it need to be replaced?
does that sound right???

Also when the car is cold the engine vibrates more than if its hot, is that true?

Sounds more like a transmission or engine noise than an exhaust problem... grinding noises of any form are bad! I'd be looking into things like the engine oil transmission and making sure there aren't any issues there.

there is no problem with the tranny, smooth as butter.
the bloke at mitsu said it was the exhaust flexi but i'm scared he is milking me.
i'm starting to think its the oil pump

get some second opinion dont rely on mitsu mech only. try like ultratune or something similar:think:

Yer they were trying to pull my leg!!!!!!!!!!!
turns out on cold start it was the alternator belt and pulley that needed to replaced. and for that other noise it was the start motor turning over, that doesn't need to be touched:D
All up fixed for $45