Best way to gain horsepower for 2005 mazda rx8 manual transmission?

Buying an 05 rx8 on monday. it only has 40000 miles and is the manual transmission (only way to go!!) what is the best way to start increasing horsepower? Im not some dumb kid that doesn't know what he is doing. I know a good start is a CAI, exhaust, chip, and basics like that.. just wondering if anyone knows what the better brands for a mazda are. (some brands work great with some cars and run like crap with others) since its a rotary it will obviously be different. Thanks in advance