OK, you guys want the skinny? 
Here is the deal. You guys are both right, in a way. The way the engine is designed, It requires 2 sets of plugs to "complete the burn". Plug 1 burns, gets most of the fuel, Plug 2 burns (iridium) and gets whatever is left. They fire ALMOST simultaneously, literally less than 1 degree from each other. It really is a fascinating system. I am not sure which ones fire first on the 4.7, but I am pretty sure it is the coppers. I will have to do some research.
The factory part numbers for the plugs in the 2008+ 4.7 are: Upper Bank — FR8TE2 (Gap 0.039 in [.99 mm]) Lower Bank — FR8T1332 (Gap 0.051 in [1.30 mm]). You can adjust gap to your preference, mine is slightly over on the upper bank, and will be slightly lower on the lower bank when I change those. FR8-TE2 is a Copper Core Bosch, though I am pretty sure Champion makes one as well. FR8T1332 is an iridium plug, good for 100,000 miles or more.
Sean, the way the engine burns fuel, going to a colder range plug, or a plug style like E3 or anything of the sort in the upper bank will not help, but could in fact hurt your engine's performance. At a minimum, I know for a fact in another 30k, you will be paying more for your platinum's or whatever, because the plugs in the upper bank WILL go bad in 30-40k miles, due to design. Its really the only way to run a dual plug setup. One set is gonna burn out fast, and its usually the one that fires first If both sets are iridium it throws off the timing of the spark due to resistance, and could potentially screw some things up. I doubt it would do anything major, but you might blow a coil. I know the E3's blow coils on both the 4.7 and the 5.7, because I have put them in, gotten 3 feet out of the garage, and gotten a stumble and misfire in cylinder 2. I put a set of OEM plugs in, changed coil #2, and went on my way with no issues. Had a friend try them in a 5.7, blew 3 coils.
I would highly recommend keeping factory plugs unless you have a reason to go colder, such as forced induction/nitrous, etc. The lower bank isnt too difficult to change, with the right tools (a couple of u-joints and extensions will make things easier.
Torque to 22lb-ft (I go to 10, 22 makes me uncomfortable with the integrity of the plug), Make sure you use anti-seize, and use the special tool to pull your coils so you dont rip them.
Here is the deal. You guys are both right, in a way. The way the engine is designed, It requires 2 sets of plugs to "complete the burn". Plug 1 burns, gets most of the fuel, Plug 2 burns (iridium) and gets whatever is left. They fire ALMOST simultaneously, literally less than 1 degree from each other. It really is a fascinating system. I am not sure which ones fire first on the 4.7, but I am pretty sure it is the coppers. I will have to do some research.The factory part numbers for the plugs in the 2008+ 4.7 are: Upper Bank — FR8TE2 (Gap 0.039 in [.99 mm]) Lower Bank — FR8T1332 (Gap 0.051 in [1.30 mm]). You can adjust gap to your preference, mine is slightly over on the upper bank, and will be slightly lower on the lower bank when I change those. FR8-TE2 is a Copper Core Bosch, though I am pretty sure Champion makes one as well. FR8T1332 is an iridium plug, good for 100,000 miles or more.
Sean, the way the engine burns fuel, going to a colder range plug, or a plug style like E3 or anything of the sort in the upper bank will not help, but could in fact hurt your engine's performance. At a minimum, I know for a fact in another 30k, you will be paying more for your platinum's or whatever, because the plugs in the upper bank WILL go bad in 30-40k miles, due to design. Its really the only way to run a dual plug setup. One set is gonna burn out fast, and its usually the one that fires first
If both sets are iridium it throws off the timing of the spark due to resistance, and could potentially screw some things up. I doubt it would do anything major, but you might blow a coil. I know the E3's blow coils on both the 4.7 and the 5.7, because I have put them in, gotten 3 feet out of the garage, and gotten a stumble and misfire in cylinder 2. I put a set of OEM plugs in, changed coil #2, and went on my way with no issues. Had a friend try them in a 5.7, blew 3 coils. I would highly recommend keeping factory plugs unless you have a reason to go colder, such as forced induction/nitrous, etc. The lower bank isnt too difficult to change, with the right tools (a couple of u-joints and extensions will make things easier.
Torque to 22lb-ft (I go to 10, 22 makes me uncomfortable with the integrity of the plug), Make sure you use anti-seize, and use the special tool to pull your coils so you dont rip them.
