I have a problem with neighbors complaining when I'm riding at night....Does anyone know of a good place to get a silencer and does it rob of the power???

 

Depending on where you live, it may be illegal to ride after dusk anyway. That aside, if you have an aftermarket exhaust, put the stocker back on.

If you have the stocker still on there, you can consider a supplementary muffler. Here are a few...
ATV Stealth exhaust
Kolpin Outdoors silent exhaust
Another one

They all run around 200 bucks, give or take andrew jackson.