The MSD coil isn't listed for the 5.9 . You need a 8228 I think . You'll also need to get an Accel adapter . Not a waste of money either . I have them on both mine for years of trouble free service . Coils are a wear item , my MSD cost me $45 at the time , I think an aftermarket replacment was $60+ (oh Canada) . The box I did use . Made a mistake in the wires and burned it up . Yet to put it back on , but , planning to when I do the engine work . It makes quite a nice difference , it's even audible . My wife immediately noticed the lack of power after it was removed .
Milan , how many K on that "failed" mopar t-stat , 100K+ ? NO you "need" Mopar , unless you want peace of mind . Stock 195 , after all , it's what your jeep was designed to run . I know I won't run anything else . Been burned too often with aftermarket stats .
Platinums a waste ? I run dble platinums . I was so impressed I just bought the 2nd set of them , even though after 30K , they run as good as ever . Milan , does your 5.9 get 18-21 mpg hwy @70-75 mph . I do . If it's not with help from the plugs , maybe it's my MSD coil , lol . I can't abuse my 5.9 enough to get lower that 14-15 avg per tank , well , I could but , let's be reasonable , I can't afford the tickets . Very quick starts . I credit some mpg results from my oil choice , Castrol 0w-30 , a true synthetic oil , not a blend . I wouldn't even suggest them if I didn't try them long term . Before that , I was Champ copper core or NGK FR's . These are much better all around but if you do want cooler , the NGK's are great .
As for upgrading the intake . You could , however I can't comment on it's performance as I don't have one . IIRC , slight low end loss for high end gain . I do know there is a list of other upgrades that is recomended , each compliments each other . Cam , roller rockers , headers , full 3" exhaust and the tune etc etc . How deep do you want to dig into your pockets ?
Headers , ignition upgrade , exhaust upgrade and a tuner , you won't be disappointed .
I have an MSD coil, I actually have Kolak's whole ignition "upgrade". I bought it mainly out of convenience since I was already placing a rather large order with Kolak. Regarding the MSD coil, it's actually pretty funny, the Jeep guys are the only people who seem to think this thing makes power. I spend a lot of time reading on the Dodge forums, and it's pretty hard to find anyone with a fast or big power dakota/ram who thinks you should use anything other than the stock ignition.
Without trying to sound like a dick, there is no way in hell your lifted 5.9 gets 21 mpg highway at 75 mph. 15-16 at 60 mph maybe, but 21 mpg at 75 is not happening on a lifted SUV.
Back to the plugs, I have never heard of anyone recommending platinum plugs except for the people at the parts store. Copper is a much better conductor than platinum. The double platinums are simply a longevity feature, but many would suggest that double, triple, and quad tipped plugs are a marketing gimmick.
In regards to thermostats, to each their own. I've never had a thermostat that I have replaced fail while I still owned the car. I run a 180 in my 5.9, but I run a 160 in my Z06. A lot of people think running a lower temp thermostat will keep the motor in open loop forever, but this is simply not the case as long as you don't go too low. For example a stock LS1 runs a 195 stat too but it's coming out of open loop around 158 degrees.
I'm with you on the German Castrol, probably one of the best 30 weights out there, but unfortunately it's been phased out now, so I switched to Pennzoil Ultra in my Z06, my 5.9 gets Rotella T, but I am considering switching it to Pennzoil Ultra as well.
Edit: Did some research. Apparently GC is being sold under Castrol Edge 0w-30 now. A few months ago, there was some speculation that they changed the formula in the US, but it appears the formula is the same just sold under Castrol Edge in the US now. Good to know for anyone who cares...