The final thing I've done so far is install a cold air intake kit from ebay. I seriously thought these things were jokes and didn't do crap to help out an engine. Maybe they don't do a whole lot for a 5.3L but they sure do help wake up a 2.2L!
The install was easy, almost too easy. Plus, you get to remove a lot of the stock crap which really clutters up the engine bay and is a total pain in the ass to have to remove to work on stuff, especially considering that the A/C lines RUN ALL OVER ON TOP OF IT. Good call on that one GM
In all honesty I did not notice any acceleration increase, nor did I notice a fuel increase. I've had it for "2 tanks" now and both were right around 23 mpg. BUT where I did notice a clear power increase was in 4th and 5th gear on the highway. It's easier to pass/accelerate now in both 4th and 5th gear. It's not an amazing performance add on, but it does make a difference!
Here's some pics: