lots of misinformation here! There are literally hundreds, if not thousands of us that have installed the Ultrapower ECM tune in our 8.1 liter GM engines in our Workhorse motorhomes. I was skeptical at first, and now have it. There has been alot of thought put into this tune, and I still haven't heard of any engines "blowing up" as someone else stated regarding the ECM tune.
It's not as if your Workhorse chassis is anywhere under warrantee anyway! This is a proven tune, and you should notice staying in gear longer, but not any MPG gain. Your engine is tuned (ECM), and not your transmission (PCM).