Function
Reduces back pressure from exhaust gases for a slight increase in power (5-10 HP).

Part numbers
• 76.14.26 Twin 90mm Magnum tips muffler for 1.8T Quattro
• 76.14.03 Centre resonator for 1.8T Quattro

Comments
This is definitely my favorite mod. The quality, fit and looks of the exhaust are first-class. But then again, I wouldn't expect anything less from an Italian tuner.
The exhaust is very quiet. The only time I notice it is when I start the engine and when I put my foot down. When cruising, it's as quiet as stock. There's a noticable improvement in throttle response. Feels like the turbo is spinning up faster. Also, the Supersprint is about 20lbs. lighter than the stock system. The pipe diameter is same as stock (2.25").
The Supersprint is not a full exhaust system. The stock cat, downpipe and flex-joint stay. The stock system must be cut and the Supersprint welded on just after the flex-joint.
I purchased the exhaust from RPI and had it installed by Westmount.

Technical Note
The exhaust flow in the 1.8T goes from turbo-to-cat-to-downpipe-to-flexjoint-to-resonator-to-muffer-to-tips.