As said its not too bad, especially since your car is 90spec already. The lighting part is totally seperate from the engine harness so you just leave the MK2 one in there. On the engine harness you have plugs F, G1, G2 and S.
S is for the wiper which IIRC has the same plug as the MK2 one, though it might not be quite the right length, worst case chop/splice the MK2 end on there, its only 5 wires and colours are the same. G2 is just MFA/engine sensors, no worries there, F & G1 are for ECU, starter, reverse switch and coil so nothing too much to worry about there either.
You'll have a few extra spare plugs that you wont need, carbon canister, speedo sensor and a few other bits n bobs. Can just leave em hanging or chop/tape em up if you prefer.
Basically it should just plug in without any messign about, wire lengths are all pretty spot on
Main issue is the rev counter, the MK3 gets the signal from the ECU which wont work with the MK2 clocks. If you want to keep the MK2 clocks you have 2 options, splice in the MK2 coil & TCI setup, or open the MK3 coil and add a wire. Both of these are in dannys thread
I like using the MK2 Coil & TCI as the MK3 coils are a bit of a weak spot, since I decided to completly unwrap the MK3 loom to rip out everything that wasnt required and add MK2 bay loom wiring in to make it a bit neater in regards to wire lengths that option was quite easy for me.
If you want to just plug n play your loom, the mk3 coil mod is probably easier. you can pinch one of the unused wires and use that, or add another wire alongside the MK3 loom. Plenty of holes in the bulkhead for stuff like this
Dont forget to get all the diagnostics wiring from behind the dash, its dead easy to wire in just a live, earth and your diagnostic wire from pin 43 on the ECU. If your loom has an imobilisor that goes between the ecu diagmostic wire and the plug, the control box also requires an ign live feed from somewhere.
Nick all the junction boxes from above the fusebox, one is for the diagnostics and the others are handy for accessory circuits.
