flashgordon666

if you pop up your bonnet and you hear rattling what is that?

shogo10

iTrader: (1)

Could be a number of things where exactly is the noise coming from to narrow it down?

dynamix

iTrader: (3)

the bonnet catch is loose

You need to give a little more information if you realistically expect people to help.

Mocom Racing

iTrader: (2)

Most likely cause is a heatshield, check the uppipe, downpipe, turbo and headers.

exvaux

iTrader: (1)

tappets,heatshield or piston deciding it wants a holiday like mine

jaytc2003

iTrader: (1)

As above, rattling most likely the heatshield, if it is a clicking then most likely the boost solenoid (assuming drivers side), ticking could also be noisy injectors and depending on the age of the car could also be hydraulic lifters, or clearances or piston slap........

Basically better description needed for a more accurate answer as there are loads possibilities