A more "aggressive" sound? You mean louder?
The one thing the non-motorized contingent is always bringing up in USFS meetings is noise from sleds.
Having installed a bunch of SLP pipes and cans on customer Axys sleds, I can tell you they can have an aggressive sound-- it just requires opening the throttle and holding it open. Now, I realize that an HPS or GGB "Mountain" can might be more appealing to the parking lot throttle blipper crowd but you have to think of the ramifications for the rest of the snowmobile community that your loud can creates.
Loud cans help the non-motorized contingent shut down more riding areas. The non-riding public doesn't want to hear your loud can. A lot of the riding public doesn't want to hear your loud can. There is nothing more annoying than listening to a loud can on a left hand sidehill with the exhaust out in the air.
There is a time and a place for loud exhausts. I've worked in professional motorcycle roadracing for 20+ years both in the US and World Championships (AMA Superbike, MotoGP, WorldSBK, MotoAmerica) Leave the loud exhausts for sanctioned events on closed courses, NOT public land.
If you think I'm some left leaning enviro weanie, you probably have never been to a USFS meeting when they are proposing closed areas. I have been to those meetings, and I continue to go to all the meetings in the 5 USFS districts that immediately surround me.
"Quiet Recreation" is the new non-motorized battle cry.
Please don't buy a loud can, and if you must buy one, please don't come to the intermountain west to ride. We are struggling enough to keep our riding areas open. We don't need more loud cans giving motorized users a bad reputation.
Rant Over. (and here come the negative ratings)