i was wandering if you could help with sizing please. I am currently running a 2 into 1 kirker -part number(-V-Twin Kerker Slip Ons & Syste 2:1SYST: HD FLST/FXST '07-09 w/O2, CHRM 128-71570)and am toying with the idea of trying an old style muffler. ie-knuckle/cigar.etc.etc and need to know the size of the header pipe. would it be 1 3/4 '' DIAMETER or larger. thankyou.