The silenced route is still a direct flow silencer so it doesn't affect performance in anyway, actually it's better than stock. The direct route is as free-flowing as an exhaust can ben. Think muffler-delete like Berk or similar.
We always test the system on the dyno in both mode to ensure performance are as stock or better.
The fact is to develop such a system we need time and a reasonably amount of customers willing to place orders before the development start...or a tuner/dealer who is willing to purchase a batch of these and handle sales.
We something similar with a few BMW tuners in Germany and the UK.
We made two systems for Leib Engineering, for the E82 1M Coupè:
And for their E92 M3 GT500
They provide their own control system, a "black box". The interesting thing it that it connects to the CANBUS interface, so it allows to activate the loud-quiet mode through the M button on the steering wheel (or any other button on the dash actually).
Check out the video:
[ame]http://youtu.be/z2B5wANALPk?t=58s[/ame]
The routing, silencer size etc will need to be defined specifically for the room available under the chassis of the GT86 and the sound of the car.