Under my xr8 at the back of the engine, theres a persistant whistle. Much like a kettle not quite yet boiled. Ford claimed it was the engine Idler pulley and that it was a $450 job for parts alone! now i know they can be sometimes overzealous on thier pricing. Is there any car buff that can help me out on this one ? ie price ? or how its different to other pulleys in the engine? is it big small ? and so on.

thanks

Which one, there are three of them, and all three of them are a piece of piss to replace.. You can get them a lot cheaper than that that is for sure. I bought 3 chrome ones from MrLandau at $300!