i run the Brison 3.2 motors. I swapped to a peace keeper and its is quieter than the stock set-up. I am not sure how much more quieter as i just bought a used DB meter off this site so i could tell you in about a month. Anyway the peacekeeper gives it a more pleasant the ears sound than that stock straight pipe which really sounds like it doesn't have a muffler. You may have to look into cans if you don't like the DB numbers of the peacekeeper.

my keepers came from j & a engneering