The only reason I think there is probs is that it feels
massively slower when the chargecooler water has soaked up a bit of heat in
traffic.
I wasn't aware it was a Westy.
The BEST way to deal with air temps is not to heat it up in the first place but that of course is down to what power you want, and what turbo you have.
What's the engine spec?
This chap from France had sensible low boost, good power and sensible ACT's because of it.