mudslinger exhaust

[1980z28]

I just installed a mudslinger exhaust from Supertrapp. I thought all Supertrapp exhaust had discs in them you could change to tune the bike better. I didn't see them in the Mudslinger. And, how do you know when it is time to change the packing? I have a Yamaha 450 Grizzley and and anxious to do what it takes to make it run better. I also intalled a K&N filter with a precharger and rejetted, although I am not sure I used the right jet. Runs a little better, but I expected more. Any suggestions?