For your exaust clearance issues there's always this option. This is an exaust a guy on another forum made so that it wouldn't stick down below the frame rails. With a little careful planning and creative fabrication you can maintain the same volume within the tubes and just change the shape, that way you create not only the clearance your looking for, but also do not create any unnecessary back pressure.
a little more information on this exaust can be found here
http://www.zilvia.net/f/showthread.php?t=171389&page=11