I was looking over one of the links to and IFS truck on the 'con and in one of the pictures one can see the IFS flexing well for IFS. This is because the truck has no lift and so there is less weight transfer from the wheel you wish would stuff to the one you wish would extend.

When you go with these 4" lifts typically the rear parts is only 3.5". I found that going over 4" cause driveline vibrations.

With less lift comes better street manners and increased reliability. Investing in gears, lockers, sliders, etc... will make for a very capable truck.

Frank