Originally Posted by
qsilverza
The Haldex system should be fine, it is reactive but you can make it offensive :) (Active) These systems run quite a bit of power through them especially with the S3's and I would imagine they would be locked up a lot of the time especially with a Haldex sports conversion which is quite common.
Are you running a 2.8 ECU or are you going aftermarket ? If aftermarket, and you are looking for constant lock on the rear diff, there is a solenoid valve that has very little electronics that could be bought for $ 400.00 but is only adjustable from underneath the car.
Otherwise as I mentioned, I am waiting for my contact to finish testing an adjustable haldex controller for in-cabin to work with the original ECU. Will let you know when I have some more information but essentially it sends tricks signals to lock up the diff as per the setting.