I found a used set of stock bobber mufflers on my local buy/sell site for $100 so thought I'd get them and have a go at drilling out the 3 plates and small offset pipes inside. 40mm hole saw on the cordless drill with extension for the second and third plates. Tacked on a 28mm stainless tip on the end so looks stock. Wow, what a difference. Sound is incredible without being too loud as the baffling is still in place around the inside wall of pipes. Have also recently installed TEC x-pipe. [email protected] pipes are about $1600 in New Zealand and these sound just as loud if not a little bit more louder so have saved myself a fare bit of money there and still have original mufflers if I ever wanted to lower the volume.