I know this is an old topic but I've just done a complete 6N2 upgrade on my 6N. So maybe someone will have some use for my reply. Do keep in mind that I've gone from a 1.4 60hp AEX to a 1.4 16v 75hp AHW...not all may apply to your particular application.
I've swapped:
- Engine and gearbox - straight fit.
- Axles - straight fit.
- Subframe - straight fit.
- Steering rack - straight fit.
- Gearbox mechanism - won't fit (unless you use 6N2 subframe).
- Exhaust - Only the middle and back box will fit (unless you use 6N2 subframe and engine).
- All wiring looms - some fitting required and majority of the connectors aren't the same.
- Dashboard - brackets on the side are higher than 6N. You'll need the 6N2 fuse box bracket as well.
- Heater unit - straight fit. (you'd have to use the 6N2 dash).
- Handbrake - straight fit.
- Floor carpet - straight fit.
- Seats and rear bench - straight fit.
- Safety belts - straight fit.
- Door cards - Lower handgrip screw won't fit and you'll need the 6N2 window strips, tweeter (first you'd have to remove a 6N bracket on the inside corner of the A-pillar). My car was a 3 door, the rear cards need to have a black plastic bracket removed at the bottom because the 6N one sits lower.
- Window mechanism - straight fit. If you are going for electric windows the connectors aren't the same.
- Windows - straight fit (for a 3 door).
- Ecu - straight fit.
- Interior filter - straight fit.
- Windscreen wiper mechanism - straight fit.
- Rear wiper mechanism - won't fit.
- Door locks - straight fit.
- Door handles - straight fit.
- Door seals/rubbers - need to be shortened, are a bit too long. They are a bit thinner as well, so be prepared for wind noise at higher speeds.
- Roof trim - straight fit but 6N2 trim on 6N will leave a small gap at the front of the car which might lead to leaking if not sorted.
I have a feeling I'm forgetting a lot more. But if you have any questions please ask