If he has a 10' with single exhaust, then yes he would be better to go with dual exhaust, and the price is fair. But the H pipe should be included and would be easier to do now than later. The H pipe improves the efficiency of the engine in the mid-range of any V-engine, which would include the 4.0 and most people like the sound with the H pipe The X-pipe is best for high rpm applications, and probably not as suited for the 4.0.
2013 MCA Edition-Sterling Grey
Roush body kit - Splitters/hood scoop
Whiteline suspension w/Koni shocks