Hi Terry,

Piston slap on 2wd is common due to the gudgeon pin design in the piston. Once the piston has warmed up and expanded slightly in the bore the noise as you say goes away. Nothing to be concerned about. Oil consumption should be around the 1 litre mark per 1000 miles. If it is a lot more than that, then you like every other cosworth owener will need to start thinkng about an engine refresh/rebuild.

Dont let cossie paranoia ruin your fun. I would aslo recommend you get the car to an expert to have fueling and boost checked. Unless you 100% sure the person you bought it off had it setup correctly.