This is how I described the basics on another thread here last week:
Some suggest removing the two engine mount bolts to drop the engine down about 2 inches, but personally I find this a pain and getting those bolts in again can cause a headache. So if I am only doing the intake I use the following method (although dropping the engine is essential for almost every other job on a WJ V8).
Remove the alternator and AC compressor (these need to be removed anyway. You MAY be able to relocate the AC compressor without removing the lines, but it isn't easy as the lines are rigid and clipped in a few places.
Anyway, remove the alternator, remove or shift the AC compressor. Unplug, unbolt and remove all 8 coil packs, all 8 injector plugs, unplug the throttle body (TB) components: throttle position sensor (TPS), the manifold temp sensor & idle air control valve (all on the left of the TB), unplug the MAP sensor (front of manifold) and coolant temp sensor (below the MAP) and move harness out of the way. Now remove the 4 8mm bolts holding the fuel rail, carefully pry the fuel rail up with the injectors and move out of the way (you can remove the fuel line if you have the correct line tools). Now remove all the vacuum lines going to the manifold and TB. Nothing complicated there but be careful as they will be brittle if you're too rough.
Unclip and remove the throttle cable and cruise cable (the cruise cable pulls forward off a peg), and slide the cables out of their brackets. Release the dipstick retaining bracket and other wires and brackets that may still be connected.
Now remove the coolant temp sensor from in front of the manifold. You will need this out of the way to remove the intake manifold. You won't loose much coolant but remember to refill and bleed the coolant when finished.
You can now undo the 10 (I think) 8mm bolts that hold the manifold down. It will now be loose. You can now carefully (and slowly) work this up and out of the valley. It will be VERY tight between where the coolant sensor located and the bulkhead, but it's a lot easier than removing engine mounts!!!! It does go, trust me. I have previously also removed the bracket above the TB, but I have managed it without removing this bracket too.
You will have a breather pipe going to the rear of the manifold (goes to the oil filler) - ensure this clears everything. You can remove if you wish, but you only need to move the manifold out of the way enough to get to the two bolts that hold the knock sensors down.
As they say, refitting is the reverse of removal - but with more blood and swearing.
I can show pictures of anything you wish as I have 4 engines here in various states of repair.
I expect I have missed something, but that should give you the basics of the procedure.
^ Was just about to link to Mick's very helpful post on my own thread- as it happens if I can't get a good connection on my knock sensor cable or if I find out they're bad I'll be doing the same thing some time next week!
Note: All manifolds are currently on national back-order or discontinued (as of November 2008)
2002: P/N 53031739AC
(superseded by P/N 53031739AD. MSRP: $264.00. Used only in HO engines for model year 2002)
2003: P/N 53013403AB
(superseded by P/N 53013403AC, then P/N 53013403AD, then P/N 53013403AE. MSRP: $153.00. Redesign of 2002 version, used in both standard 4.7 and 4.7 HO engines for model year 2003)
2004: P/N 53013403AC
(superseded by P/N 53013403AD, then P/N 53013403AE. MSRP: $153.00. Very slight non-performance changes from the original 2003 version. Used in both standard 4.7 and 4.7 HO engines for model year 2004).
Just my opinion but having changed intakes on cars in the past..not Jeeps admittedly....I think you will be very lucky to gain 5 and 5. The standard intake is simply not that bad or restrictive. A friend who did it said he could feel no difference at all. Being able to flow extra air through the intake will only benefit if a, the old one was restrictive and prevented the motor from pulling in the required air. b, you improve the flow through the engine (bigger valves, porting etc) . c, if once you improve the air getting in the engine you improve the way out!...exhaust and it's manifold and d, if over you get the air in there there is extra fuel to burn with it...although the standard injectors should be able to flow the relatively small amount of extra fuel needed. Don't forget the ho has rather more than just the inlet manifold.
Going to war over religion is like killing someone because your imaginary friend is better than theirs!
The info above it correct. The HO has better cams, valves and fair more improvements than a simple manifold change - and even then, many of us struggle to note the difference.
Some who have done the HO manifold swap have even noted a drop in torque due to the shorter runners on a HO manifold, but as said, all the later ones had the same intakes anyway, and the stated power output was never revised.