Not leaking exhaust so what else is there...

[Aybesea]

I have a Polo 2000 SE 1.4 8valve and i have this strange noise which has started.
On start up and after even when engine is normal temp i have this noise which sounds like a cross between a leaking manifold and a metalic sound can be quite loud,it only appears under load eg when accelerating and if i lift pedal so there is no loading on engine but still going along ok it disapears.Also on idle there is no noise atall apart from noisy tappets.If i push the clutch in while moving underload the noise goes so it seems to be only while car is moving and engine under load. This has me baffled but problem is i cannot really test it as i need a rolling road because thats when the noise is there.
Any clues as to what it might be anyone The car runs ok with no problems atall ie lack of power etc.

[blackertracker]

I had something similar sounding on my Golf Mk4 - several of the clips that hold the exhaust heatshield on had rusted through allowing it to vibrate against car underbody. Worth checking maybe?

[Aybesea]

Well after putting up with the weird noise i have finally found out where it was coming from .It is from a cracked manifold on number 3 cylinder ,so thinking it was coming from a blown gasket and while trying to replace that that is when i found the crack.However now i need a AKK manifold easier said than to get one.Does anybody know if a AUD manifold will fit( more option).Look the same 4 bolt pipe connection not sure on cylinder head connection other wise it is a new one I have to get