Here's a few thing you'll want to do before you even bolt any crap on (!) :
1- Dump the airbox and get pods.
2- Find the good jetting for your elevation (You might be too rich)
3- Clutching: Dump tyour salad bowl primary and get a better one (either TRA2 or 3 or a P-85 cut for your output shaft) and tune it right. Some on this forum will tell you to go Arctic Cat Secondary. According to me, the stock button secondary works ok if you find the good setup for your application.
These are the 3 things that hold back the Hawk from performing "ok". You already have the Jaws Exhaust if yours is an Outlaw. Exhaustwise, you can't do much except if you don't mind an extra 20 pound at the front (for the trail legal MAttech exhaust). Silencers : I only know of Turboal (thesledshed.ca) who builds some for Hawks. I've got one, works good on the type of terrain I ride (mountains) and won't crack or explode like stock jaws. The clutching is where most of the gains will be.
One awesome thing about Hawks is that you don't need that much power to have fun ! Just learn to whip this 600 around really good and you'll quickly come to the conclusion that it's the best toy you'll ever have !