I have a bunch of questions...

[Tiger Bait]

1. I don't recall anyone on the forum having done a lift, but I think the consensus from other threads is that it is not favored.
2. XM is great I have it installed and also have it for home. I think you will find a consensus here of those who have it, love it.
3. That interior is very nice. If you do more searching, you will find it is the interior from the concept H2 that GM and Hummer built for the car show circuit and isn't available anywhere including the guys who have posted the picture on their site.
4. The performance upgrade seems nice, but too expensive. If you want go fast, buy a 'vette or viper.

checking the other things available on that engine upgrade site, their entertainment system upgrade is about $5000 over priced.