I'd keep the stock thermostat and 104's aren't needed for that size pulley drop.

I'd go with AL 605's in the copper cores, those are 1 step colder than factory.

Then just build an intake for $50 bucks, spending 100-250 on a vendor intake gains you nothing.

Careful with the catback systems, most will make your ears bleed. The 3800 sounds terrible with aftermarket mufflers, besides maybe borla mufflers. Also the pipe sizing is plenty fine for 300 horsepower so you won't outflow it.