so I would like to shorten the exhaust on my 2007 S40 650 to one like a bobber, and I understand I need to keep a certain amount of backpressure so that I don't burn out the valves and guides...

There are some baffles on the link below,,, I am wondering if I can disconnect the muffler and install a baffle at the end of the header.  Has anyone tried this and if so how would it work out for me?

http://www.jpcycles.com/2007-suzuki-s40-boulevard-s40k6/exhaust

Yes I know I have to rejet in the future prolly to around a 150... but could I run this without the rejet?  Just finding out things now so I can plan ahead...

No you can't run that without  a rejet...

I'd recommend adding at least a foot of pipe with the baffle,... and with that, you'll still see significant loss of torque, finicky jetting, and obnoxiously loud...

Straight pipes are for drag racers.... only good if you want to launch at 4,000 rpm every time you take off...
Your clutch can handle 2 or 3 of those, and then it heats up and wants to take a nap for a while...

Normal take-offs will feel like a 250...  a very loud one!... ...

That would be better,... but expensive...

more ideas here...
http://suzukisavage.com/cgi-bin/YaBB.pl?num=1298689417