here is what i have so far on my 1450. the steel is from a bed frame and the muffler is off of my racing honda trx450r 4 wheeler that i put an aftermarket exhaust on.
This is the first real chance to get at my new mower. gonna have to redo the carb, tube the rear tires and add flextube to finish off the exhaust.
total cost for my mod:$5 for flex tube. these exhausts should be easy to get ahold of as almost anyone that buys one of these 450 class quads removes the stock exhaust. i would say 5 to 20 bucks on ebay.