Just get an S3 cooler... good enough for upto Stage 2+ Ko4...
Cheers Dom, will keep an eye out 
FabFreddy has one for sale, it's a plastic end tank one, but it's not supposed to make much difference, but for that price you can;t go wrong...
Otherwise theres darkside developments that do the s3 intercooler(alloy end tanks) for £262 delivered with the clamps/bolts required...
Or there's currently a THS Revo one for sale in Parts section...