Fast355, I'll try out your settings as soon as I've run a baseline with my cold air intake on.
The van has a stock air intake pick up point from behind the grill but because I don't have a hot air riser tube from the cast iron exhaust manifold anymore (due to now having headers) the air cleaner housing has probably been stuck in the hot air position. I just fitted a small self tapping screw to hold it in the open position. It's 1 degree C outside at the moment so I should have plenty of cold air :-)
Dave W, that's a very cool spreadsheet. Could you tell me how to do that or provided me with a link that shows me how to set it up?