Check out the link below. They create their 7.3 tunes from scratch on a dyno and keep timing, etc as low as possible. I have one of their chips that has six positions, my chip has stock, high idle, daily driver, tow, economy and hot. I keep it on stock unless I'm towing.
They have a chart showing the hp gains for each tune. No other mods needed, although I did a 4" exhaust on mine also and boost and temp guages. I did a lot of reading as I didn't want to damage anything. I came to the conclusion that these were the safest tunes.
http://bdpshop.com/