Get a short ram intake
I think those take away the most power

 

ive had stock, k&n v.2, and AEM. The k&n is nice and loud. but it gets really annoying after a few months. So i sold mine and got an AEM intake from a friend. I'll never look back. AEM sounds great and sometimes is louder than my greddy exhaust. Its filter is lifetime reusable like the k&n but you need to remove the front bumper to get it off. with the AEM you get colder air into your engine being that it is a cold air intake and the k&n is a short ram.

 

The stock intake system is more than capable of meeting your power needs. Any other intakes either rob you of power or simply create noise.

Find a nice drop in filter and keep your stock airbox. Use that $300 on something like brakes, suspension, or exhaust which you'll get much more enjoyment out of.

 

https://www.rx8club.com/showthread.php?p=2799276

 

Just take off the stock box remove the side screens and put it back on. Its an old trick to let more hot air in to your intake in the summer time

 

I suggest you overnite parts from japan.