on the4 X-Dyno the RB C6 on the 2045 made 1.15 HP with a very weak power curve.... withthe 9853 the motor has a broad flat power curve and makes 1.45 hp...the TQ was also higher across the board with the 9853........... the RB 2045 is EFRA legal..so its a noise restriction pipe...a 9853 is not EFRA legal, and its designed for engine output, not noise restriction......I am sure the 2045 works fine, but its definitely not the most suted pipe to make the most output.... its obviously a pretty restrictive pipe.....