I'm looking to fit the Waeco MS-50 cruise control kit with a standard audi cruise control stalk, as I want to retrofit cruise control to my 99 A4. The servo is vacuum operated and requires a vacuum source, presumably there is an existing pump. Is this easily accessibly on a 1.8 A4 and is it a constant vacuum source or does it vary depending on the load, e.g. brakes? Also how easily accessibly is the drive shaft as it requires a magnetic speed sensor to be attached to it. Not too sure so thought I would check first!! Thanks!