I've considered a more efficient radiator because keeping the engine cool when towing is sometimes a struggle with some of the hills we try climbing (Mt Ousley, Mt Victoria, Thunderbolts Way, Cunninghams Gap, Alpine Way just to name the worst we've hauled a caravan up).
I've not considered an intercooler, but then I'm not chasing more power. If I was spending money looking for more beans, I'd probably look in this order:
1) Diesel gas
2) Chip (done after the gas so it's tuned for the gas)
3) Water/Alcohol Injection
4) W2A Intercooler (more efficient than A2A)
5) Exhaust
Items 1 and 2 would be responsible for the majority of the extra power, the other 3 would provide small increments that add up but on their own are minor.