I’m pretty sure on eBay Ive seen a bracket that bolts onto the actuator mounts and clocks in to valve “key way” to lock them open Audi/VW. Or ask the exhaust shop to spot weld them open when they fit the exhaust..
The tail pipes will need lengthening to suit the Tiguan outlets. The muffler itself is held in the same position by the same mounting system.
To keep the cost down do the following:
Remove plastic factory “fake” tail pipe exits from the bumper so the exhaust shop doesn’t have to.
Wrap the reverse sensors wiring in the rear bumper in heat proof wrap in the vicinity of the new dual outlets. (I think I even rerouted 1 away from the outlet position)