It's actually pretty easy: My Profile Designer » QUADCRAZY ATV Community
In the Custom CSS section, I added a myspace 2.0 thanksgiving theme I found on a website online,that's it!
Keep checking ebay to see if someone lists a stock system that they took off, that's my best advice for you. You can get the entire muffler assembly stock for around $250-$275 from what I've seen from places like bike bandit and cycle gear.