is the only difference in the 07-08 exhaust systems the O2 sensor bungs? If I got a system made for an 07-08 and I plugged the bungs, would it bolt up to my 06?
I don't know if the entire system will fit, but the mufflers sure will. I installed a set from a 2007 Street Glide on my 2003 Ultra. The bike now runs and sounds much better due to less restriction.
I called Vance and Hines for this exact reason. The six speed trans is a little larger and the bends around the trans are slightly different. He said that it may still fit, but the bends are different to accomodate the trans.