HP Design Wheels

I'm planing on replacing the stock wheels and I saw the HP Lightning Hypersilver wheels and I think that they look good. I can get them from ebay for $800 so not too expensive. I want them in 18". Now, should I get them in 18x9 or 18x8? Some one have seen them on a 2005 Mustang, or better yet, have a pic? Are they any good? Any information will be apreciated.

Thanks

Diego