Thanks guys!
That first exhaust I tried was nothing more than the telescoping pickup tube from a 55 gallon drum pump (i get these at work for free) like this:
http://www.lyndist.com/drum_pumps/381.jpg
It worked ok (I rode 60 miles with it) - but I didn't get the lower telescoping part to quit rattling before I found the 'machine gun' tube and decided to go that route.
The seat construction was real easy with nothing more than hot glue, staples, 2 layers of cardboard, duct tape, white beaded insulation foam & 18" x 24" piece of black vinyl from fabric store. I also put in a support beam from an aluminum 'L' piece I had left from fabricating the tail light support pieces. The aluminum support beam is duct taped to the seat itself and uses 2 factory screw holes for easy mounting to the bike frame. It's more comfy than it looks...
Fun fun fun! Been riding it a bit too - seat is comfy enough so far, stiff but not unbearable at all :2tup:
gotta go ride some more !! :rawk: