I'm relatively new to this forum. Just bought a Duramax. Got 375 miles on her.

Can somebody give me a survey on power chips, or anything similar to such that give the 6.6 more power? Do these upgrades increase fuel economy, and how do they affect the engine in the long run?

Get comfortable and do some searching. You'll get a lot of opinions about power adders.

Here's my .02.
A lot of it depends on what you want to do with the truck. If you add 90 or so hp and the TQ that goes with that tune you can run the risk of limping the allison. If you tow and want a little bit of power the Edge EZ seems to be a good fit. If you are just going to tow the TTS tow tune is a good one. If you want to have some fun get some guages and then you have a lot of choices on programmers. I personally run the Edge with Attitude and the Predator. Of course I do that with an upgraded tranny. If you are not planning on upgrading the trans stick with a less powerful box. The power is addicting and the tranny will eventually start slipping with too much power.

The tuners can increase fuel economy a bit but you have to keep your foot out of it to get any benefit.

Like anything else, keep your goals realistic. Don't expect to put down 600 horsepower without some major headaches and cash!

Also, don't expect to gain a whole lot in the fuel mileage department. I've seen AT BEST a 1.5 MGP increase while using computer enhancements. The good news is that fuel economy doesn't usually suffer significantly, if at all, when putting lots of power to the ground in these trucks.

My advice? Get gauges first to monitor exhaust temps and turbo boost. Then start playing with small (~50 rear-wheel horsepower or less) tunes to see what you like. Much more than that on an LLY engine, and I'd look seriously into transmission upgrades.