Bomba6: you can check the video how you can improve tour Psr's drums without changing your Yamaha arranger. You can buy a sound module or use another keyboard. Check this video: http://www.youtube.com/watch?v=xhY_t-NajR0

Ps By the way your nickname in Spanish means "bomb". Kind of funny coming from Israel. No offense I'm a (non religious) Jewish too.