You wouldn't have to do much to put it on, problem becomes the huge hole you get where the stock exhaust was, there is a subframe thing under there that the exhaust normally hides. It is very ugly once exposed. This is assuming you mean 03-05 R6 slip-on. New R6 exhausts can fit, but require more modification.
yea two brothers makes a mid pipe that goes on the side and would fit perfectly under the tail. I just dnt want to spend 800 bucks for a danged exhaust setup.
This is what it looks like with an R6 exhaust on. This is not my bike btw. I prefer side exhausts too, but that big underseat gap has kept me from changing over. I've only seen the shorty exhausts used. I'm not sure which one you are planning on using. Did you mean one like this?
You can always get a Scorpion exhaust, a lot of people have them on here. Its made for the FZ6 so you don't have to worry about fitment and you can get them for under $500.
I'm not sure I understand fully. You mean get the R6 exhaust and then modify it to go under the tail? I guess that could work, just be careful about the swingarm potentially hitting it since it would be coming from the side. It might be easier to just buy the muffler and have a place make you a custom midpipe that goes through the swingarm like our stock exhaust. People have done that before. I think the majority of the cost for our exhausts is because it uses two mufflers. The pipe in itself doesn't cost too much.
save up man.. or just go sell a bunch of old stuff on ebay.. my guess is you really wouldnt be happy with the "space" that opens up from changing out to a single muffler.. good luck