The Miata came with some sweet stickers. I estimate they were good for an extra three horsepower, but they were a little "ricey" for me, and I think they would attract the wrong kind of attention from police. There's enough to attract police on this car without the stickers.
They peeled off pretty easily, but they left the typical residue. A little acetone took it right off.
There was also a Mazda sticker on the driver side window.