I have a 2005 Bonneville SE I am looking to Mod my exhaust to a SLE or GXP type of exhaust. Where would be the best site online for something like that. I have tried google and no luck maybe thought I would ask here if anyone had any ideas. I hope to spend around 800 for this exhaust.

Unfortunately the only option is from the dealer. The best mod would be to install TOG or SLP headers or go with aftermarket mufflers and have a local exhaust shop plumb up some custom pipes.
Since you are not supercharged you may be best to simply change your tips or go to larger exhaust piping after the resonator. Magnaflow or Flowmaster mufflers sound good.

There are a couple other members that have modified the exhausts on their SE'*, they will probably chime in here soon. BTW, real sharp looking Bonneville there.
Welcome to BC.

If you want the GXP sound, you may be able to just go to the dealer and get a GXP muffler and install it in place of your existing muffler. Is that what you want? Or do you want the duals?

I am interested in this as well, especially the duals.

Theres is a post with the GXP muffler part number... And in the same one with the SLE number. If I can't find it I can tell you what a 2005 SLE has? :?