[Mr.ac]

For what you want it would be three options:
1. ECU tune aka Open Flash Tune or equivalent
2. Free flow exhaust aka Headers and muffler
3. E85 fuel.

All those can be done with under $1000 give or take if it's on sale/used what not.

As for personal preference, neither are not worth the price for the gains. If you want power that is worth it, save up or bite the bullet and get a turbo/super charger. But that's just my opinion.

As for the cold air intake, that's really for pre direct injection cars. Ours are pretty good from the factory.