I have an 05 Touring Roadster that had a blown engine and the Reman co sent me a RevUp by mistake and instead of waiting a few weeks to swap out for the regular DE I decided to go through with the RevUp Swap as the reman co would foot the bill for the additional parts (Hoping they stay true to their word)
I'm in the midst of this and about 99% done and it SUCKS.

The forum posts would lead you to believe that all you need to get the RevUp working in the lower models is the 06 Harness and ECU as well as the additional exh cam sensors and if 03-04 the wideband o2 sensors that come on 05-06 models.

Sadly there is no mention of also needing two of three sub harnesses. Added to the 06 Main Harness, you also need the Harness for the rest of your Ignition Coils, The EGI Harness is slightly different but the one on my 05 could be reused and lastly there is a short 6" harness for one of the 2 plugs that dumbfounded me for 2 days which is for an Oil Temp sensor (same sensor used for coolant temp) as well as the sensor you will need.

So as I mentioned I had two mystery plugs, 3 actually but I'll get back to that.
-So the 1st plug was a brown two pin female connector on the same section that feeds my PS pressure sensor, alternator and oil pressure sensor. The 05 did not have a 4th connector there, two days of digging and looking for help, the Parts Manager Brad at Alhambra Nissan (On the other side of the country and not making a dime off me, BIG THANKS for the help) figures out that not only do I need the Sensor PN 22630-ED000 $41.13 but I also need a 6" harness to connect the sensor to that brown plug PN24168-CD000 $15.83 Order placed and waiting on the harness.
- Second Connector is a Gray square with round edges male connector that is on the same wire run as the secondary O2 sensors and Crank position sensor, runs right between the engine/tranny and near the PS rack. So I assume its either some sensor that goes to the PS rack or maybe something to do with VDC vs TCS? (Still havent figured out if I'm going to hit a wall and find out I have more issues since my 05 Roadster has TCS Stock) This time Brad sends me an 06 harness schematic with all the sensor names and locations I figure it out and pull up a parts site and see the pic of the 06 rack having a plug for a solenoid on it. Call him back and a few minutes later he send me my worst nightmare, about 12 pages on the 2 different rack systems they used in 06, of which I figure out that I have the Type 1 system. I also find out that beyond an $1100 rack, I would also need a $600 PS Controller that mounts up by the right kick panel and most likely another small harness to go from the gray plug to the Racks solenoid and god knows what else.....

So my point with this thread is to A) point out to those contemplating this as an easy swap, that its a PITA in some ways, and B) if anyone else has had experience doing this swap did not doing the PS Rack setup from the 06 cause any issues or CEL?

 

Patience is a virtue. Props for having a go at this, all I know is that its not just a case of putting the engine back in the bay and connecting all of the electrics and pipework. I read on another site about a guy who tried the same thing as you and, like you found it a pain in the ***. Good luck with the rest of the build. If I can find the site & link I'll send it on to you.