Having bitten the bullet and put a turbo in the +6 I would think a turbo 2.0 litre would be the natural way forward.
The wonderful thing about turbo petrol is you can tune them very cheaply with a remap.
I had a BMW 220i and the standard 190 bhp was plenty for me in a heavy car.
If, like Madmax, this may not be enough for £350 for a remap you could increase the power by 80 bhp.
This may sound dangerous but this is the same as the 228i produces from the same engine.
