A generic map will do for no mods and up to intake, cooler and full exhaust inc down pipe. From there you can download further maps to make the most out of those mods.
About 300 ish bhp. After that you're looking at RS injectors.

If I'm wrong in that thinking someone will correct me.

For your budget map and a cooler.
The most restrictive part of the exhaust is the down pipe I'm led to believe so work from there back I guess.