hi all, i have a 05 ST with 58k on the clock ther is a rattle from around 2.5k revs when the engine is not under load, it sounds like a top end rattle as if a tappet is stuck or somthing, are these on hydro tappets & has anyone had a similar sounding rattle? thers a vid on youtube of someones rattle & its excat same as mine but doesnt say what it is.