Yes, hydraulic launch coasters make great sounds. The best sound that any roller coaster makes would have to be El Toro. The roar it makes of the first two airtime hills is amazing. The Rolling Thunder crossover airtime hill is even better. The noise that coaster makes is just like nothing I have ever heard from a roller coaster before. Check out the El Toro video I made. At the very end, when the music stops, you can catch a few seconds of the noise El Toro makes.
http://www.youtube.com/watch?v=nX880PN1vaI