Cobra makes a backrest removal kit, which removes the sissy bar but allows the turn signals to be mounted in the stock location. See this link, about halfway down the page:
http://www.powersportspro.com/trcata...0203c0421i.htm
Or you can relocate the turn signals to the license plate bracket by using the adapters at the bottom of this page ($37.99):
http://209.15.36.61/swcart/shop.cgi/...D=PUT_SID_HERE
After you relocate the turn signals, you can use a couple of chrome sockets as spacers where the lights used to be, between the fender and the rails, to allow you to remove the sissy bar.
2005 is the first year without a sissy bar on the Intruder 800 (now called the S50), so you can order new fender rails from the dealer, but this is by far the most expensive of the three.