Go for it Trev !~
Heck at least around here in PA ...Drag pipes are NOT LEGAL on HD's ...but they sound so darn good that I have never been stopped for my Harley soundin good & loud !...It is up to the Officer to make the decission of if it offending and in 20 yrs ...Ive never had one stop me ...but with Mufflers like you are thinkin ...what is difference if they exit from in front of the rear wheels , out the back , or stright in the air in stacks ??...I really dont see a prob ...especially if ya make it LOOK good ! ...they will be lookin at ...MAN YA SEE THAT COOL OLD TRUCK WITH THE STACKS !....not the law book ! ...lol
