My guess is that would be a 5-10k mod. The exhaust is gonna have to be custom made , then you have quite a bit of body work and I'm sure re routing of things. I think it would be very expensive. What may work a bit better would be a side pipe that comes down under/behind the side skirt and exits in front of the rear wheels through the side skirt. I would think that would be the way to go, lots cheaper. Then you have to figure out what to do with the back side because now you have a big opening where the exhaust once was.
Pat