Akrapovic Slip-On Line (Titanium) - Porsche 911 (991) Turbo | Turbo SThe Akrapovi? Slip On Line for the Porsche 911 Turbo Turbo S is the first stage in the exhaust tuning process and gives this already outstanding car a further step in performance. Made from a high grade titanium alloy and finished with exquisitely handcrafted carbon fibre and titanium tailpipes, the Slip On Line reduces weight to aid with handling. Akrapovi?s sound engineers have also created a deep and unique sound to make the Porsche 911 Turbo Turbo