Just been researching but can't find much info on this. I only ask as just had my s3 mapped at celtic tunning and they said the haldax was pulling the car back on the dyno! And as a result my dyno graph is all over the place! No smooth power curve and not accurate on bhp and torque. They did not want to pull the fuse as thought it could damage the haldax controller. But I hear a lot of tuning firms map 8l s3, s in front wheel drive. Anyone had any experience in this?