The only ignition upgrade that you might need would be to convert the current 3.6 ignition over to higher output ignition on the later 3.6 pentastars.
The newer spark plugs are different - slightly different heat range, I think.
And the coil packs are different. The newer coil packs have three wires going to them versus two on the earlier coil packs.
If I understand the wiring correctly, the original coil packs have two wires going to them, a ground and a +5vdc trigger from the PCM.
What I believe the third wire adds is a+12vdc power source to the coil to give it a higher voltage on the primary side of the coil. Still triggered by a +5vdc signal from the PCM.
I looked briefly into aftermarket ignition systems that might work and could not find one or even just upgraded coil packs.
Probably you don't need to do this anyway unless you are stressing out the current ignition system by using forced induction and perhaps doing water or water/methanol injection on top of that. There's only one person on this forum crazy enough to do that and he may be lurking in this thread.