A buddy has some real short pipes on his S50, and it sounds very loud and harsh, too high pitched for my taste. He likes it though.
For a free (or nearly free if you need to buy the drill bit) try MY EXHAUST MOD. It sounds deeper and louder than stock, required no rejetting, and is a lot cheaper then new pipes.
lus1: for Dr. Bob's exhaust mod.
I love it - and the guys I ride with think it's great too! When we ride through tunnels, they can't even hear their own bikes if they're following me.