320, if your engine bay is anything like that on my 1998 saab 900 turbo with the 2.0t .. you should be able to quite simply install a filter in place of the stock air filter box, and it will suck in HOT air. In fact the shiny turbo heat shield you see there, I had made to lower intake temps since the stock one was missing. If I remove it, intake temps rise like crazy.
Fabricating under-body flat panels will be a great addition. Lowering the vehicle helps a lot, though most people on here aren't interested in that sort of modification it seems. Lower you are to the ground, less air travels under the vehicle / simple / cheap.
Blocking the intercooler would be a no good idea unless you fabricate an under-car airdam which directs airflow over the intercooler - the engine will run too hot under boost and high loads without sufficient air passing through it. (especially with a hot air intake installed.)
Fashion some wheel well covers for a cheap removable way to increase gas mileage.