Under recent benchmarks a type-R sticker gives the playstation 2 rom drive a boost to around 30K rpm's -- of course now you will have to buy games pressed on premium media so they dont become unstable and explode in the drive.
before it gets ugly, its for dvds, not games. and stickers won't add enough power for my taste. i need to cut holes in the body and put neons lights in it. that will probably up the rpm of the drive, double the memory, make the tray open faster and hopefully make it run faster than my xbox.
Mine has always read -R discs without a problem. I have the older system as well. Supposedly, the units produced after September of last year have a better drive in them and improved support for both + and -.