Bought my first modern diesel... 2005 Silverado (LLY duramax). Got what I thought was a really good deal on it, and above all, I really like it, so that counts the most.

The truck has an aftermarket exhaust on it of some sort. Not sure if it's an aftermarket downpipe or not, but it's certainly a down pipe - back system. The truck also has an Edge device mounted in the upper console, however it doesn't appear to be working. I push all the buttons on it and it does nothing. How can I start diagnosing this?

Looks to be a stock intake on the truck. Any easy bolt on recommendations for the truck to make it a little peppier?

Quick pic: