Appearance Modifications
The single most important step you need to make before making any modifications to the appearance of your RX-8 is to grab your favorite beverage and start reading this thread: RX8Club.com: What Not To Do To Your Car. Yes, it's long, but it's mostly pictures. Lots of pictures. Hopefully, you will be laughing in shocked horror. If you find yourself thinking ANYTHING in that thread is "cool", "appealing", "attractive", then please find your wallet and hand it to the next homeless guy you see. He will spend your money FAR more wisely than you will. I'm serious.
So you found something you like?
Pay attention to quality. You WILL get what you pay for in quality, fitment, paint, etc... Most aftermarket body parts are made by manufacturers that figure that "close enough" is good enough, and there are fitment problems with almost all of them, or problems with cracking, splitting, etc...
Beyond that, everything is a matter of taste, what you like, and what you don't like.
Pay attention to quality. You WILL get what you pay for in quality, fitment, paint, etc... Most aftermarket body parts are made by manufacturers that figure that "close enough" is good enough, and there are fitment problems with almost all of them, or problems with cracking, splitting, etc...
Beyond that, everything is a matter of taste, what you like, and what you don't like.