I haven't done mine, but from what I hear, a chip and exhaust will make a world of difference. It appeears that a Westers tune is the way to go.
Check out http://www.fullsizechevy.com/forums/ . lots of good info there.

 

WoW, Thanks. That website is full of info. :beer:

 

The injectors and FPR are known issues after 100k miles. Some have reported soft cams that go flat. A tune is a must especially if your running the 4l80e trans. Headers would be nice but they are pricey if you keep the emissions. The FSC link has lots of info read all 80+ pages. http://www.fullsizechevy.com/forums...ms/general-discussion/technical-maintenance/213662-96-99-454-vortec-owners.html If you're planning on doing a lot to it I would save your money and go cummins. You could easilly dump several grand into this engine and it will still get left by stock diesels, and get half the MPG. I tow with a 99 454 and some day it will get a 12v dropped into it.