scruffy, don't apologize, its something you definitely want to take the time and get right. Have you considered going with something like my Forgestars, where you can get the offsets you specifically want? The price may have gone up, but mine were 1200 for the set directly from them.
Martin,
I was bottoming out in back too!
I forgot about that part. My exhaust flanges got ground down a bit. and my original undertray looked like yours when I replaced it.
