Rockers

[Saints]

Looking for a set of rockers and shafts for my 450, which should I look out for steel or aluminium seen both types, also does anyone have either a new unused set or a vgc used set for sale. I bought some used ones which were looked ok with little use but still getting slight noise.

[QBee]

No idea how expert you are. A common cause of a tappety sort of noise with these engines is slightly leaking exhaust manifolds.
Easy to test - piece of rubber hose (like you would use for a propane bottle on the barbie), little bit of thin copper pipe in one end ideally to stop you melting the rubber on a hot manifold.
Stick rubber end in ear, engine idling, listen for louder noise, especially around the gaskets and the 4>1 union.