I build for my supermono an exhaust system using bent and straight parts from a 600 supersport 4-1 and it wasnt that much fun, and that's just one cyl (albeit twin port exh). doing a 4 cyl, accounting for all the angles, lengths, spatial position while you tack everything together is going to be a nice little nightmare... not to mention welding thin-wall tubing challenge. really doubt the benefit vs headache...
