I'm "planning" and engine swap in to my s5 n/a.
Now it won't be until march so I've got time to collect parts and do this...
I've got the s4 TII ecu and emissions(Passenger side) harness.. and the knock sensor box.

The question I've got is I'm sure this has been covered somewhere... so where are some threads as my search came up empty... lol.

And, I know that you can just adjust your n/a harness, but seeing as mine is a different series and the s5's have the electronic MOP's... I'd rather just use the s4 items..
Would I need the Body harness and the Dash harness as well?

Also... as for my poll question, would I be better off just buying a s4 shell? lol.
My s5 is really rough anyway, but I'm emotionally attached (3 years, three engines, etc. etc.)

 

If you want to keep the shell get an s5 motor. All the electronics are different and nothing will plug in so you will have to buy all s5 electronics for the s4 motor. I did it the other way, s5 TII into an s4 NA. Regret it, to this day car has a horrible hesitation that no one can figure out. KEEP IT IN THE SAME SERIES!

 

? but if you've got all the right parts and wire up all aftermarket gauges the engine should start and run fine right? As long as you plug it all up correctly...

 

Well Gauges have nothing to do with the car running right,but the wiring certainly does.
The Best bet to save hassle would be to turn the s4 engine into an s5.
Remember that Pesky OMP?..that needs to be there when you have the S5 ECU in the car.
The way that you can get around that is to get an RTEK though.