Borla 14-18 Silv/Sierra C/B Exh ATAK 1500 5.3L V8 AT/MT 2&4WD Ext Cab(78.7) Crew Cab(69.3) 143.5 WBBorla 14 18 Silv Sierra C B Exh ATAK 1500 5. 3L V8 AT MT 2&4WD Ext Cab(78. 7) Crew Cab(69. 3) 143. 5 WB The Borla 140797 ATAK(r) Cat Back is tuned for sound and performance specifically for the 5. 3L engine in the Silverado and Sierra 1500. For the owner who is looking for an aggressive and head turning sound, we recommend our ATAK(r) system. It provides a drastic difference in tone and overall volume from the much quieter stock exhaust system while