I just did this conversion to my '05.
I was having trouble finding on eBay any good condition stock '05 mufflers and I was able to get a super deal on a 2009 Stainless system.
The header pipe lengths are the same but the muffler side is different. The mount in the mid section that bolts to the frame is in a different location (further back) then the steel frame location. I made a bracket that goes from the lower side panel bolt to it.
This will then bolt up to the rear mount just fine.
The major change comes with the header pipe. It needs to be lengthened 1 1/8" so I went down to a local muffler shop and the guy was nice and welded on a piece that length to the end of the header that fits into the rear muffler section. Make sure you de-burr any extra metal shavings or cut areas.
That's it. just make sure your gaskets are good and bolt it all up.
Posting some pics that will clarify it.
I don't have a pic of just the header pipe but you can kind of see the weld.