illlook into leaky inlet gasket as it sounds to be that area,it doesnt smoke is the quietest cvh ive heard from cold just this idle issue was spot on when i bought it but always the way.ill take the inlet aprt and do gaskets

also i thought it may be dump valve but its a near new forge one but u have to cain the car to get any sound but it is running near standard bhp and i want that chavtastic dump valve off anyway so just bung it up will run better without