I've just read a interesting article on intercooling that offers some interesting concepts.
Because my car is missing it's small radiator I'm going to try a couple of experiments. I'll start off with a static amount of water to see if that improves things at all, if it does I may try the candle wax idea. I'm also going to try getting a small radiator or larger heater matrix from the scrap yard and try that too before I pay for a new one from GSF which are around £70. In fact if it works well I may not bother with the pukka thing.
Steve.