Top 5 upgrades?

Hello all. I'm about a month in my new '03 Yukon and I am starting to research upgrades. I don't want to necessarily copy what everone else is doing, but wanted to see what you guys thought were easy, nice and somewhat cheap upgrades. I know a lot of people are getting parts from Denalis and Escalades, so you can include these if you wish. Thanks!

KRS

Man, this board is D-E-A-D!

How about just this one then....has anyone installed the K&N intake? Happy with it? How much louder is it inside the truck?

KRS