Hi guys, just a heads up for anybody interested I've put 3.66 gears in my 350.
The transmission behaves OK, holds gears a little more in sport with normal driving, OK if you get stuck into it though (onyl time mines ever in sport)
This is definitely how the car should have come from the factory, 0-100 may have been effected but overall it is a much nicer drive, not as full on as the 4.1's from the 2IS into our cars