Akrapovic Exhaust System for Porsche 911 Turbo/Turbo S (991.1)S PO991TSO HT SO Slip On The Akrapovic 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. Akrapovics sound engineers have also created a deep and unique sound to make