I had a buddy tune my 05 Yukon XL. He turned of the DOD for me and made some other small changes. We changed some things in both the normal tables and the "Tow/Haul? stuff too. It's like having a normal and a "performance" mode now..hehe!

Stock tunes are usually pretty conservative, understandably. And not that you will feel a "new truck" once you tune but, by changing up the shift points and dialing in your mixtures etc.....at the right price it's worth it if you have a good tune for your specific rig, NO DOUBT!