Great setup you have out there

and for your information changing your mufflers wont add any extra HP but you will have a new
rhythm 
You might go and get X pipe with 3" down to the stock mufflers
P.S. Do not listen for what ppl say in SS4ever about
gaining more from your setup, what you just did is great. Enjoy it
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2010 Black/Black SS RS M6, ARH headers, Hi-flow cats w/x-pipe, Fastlane CAI, Livernois Camshaft 2C, SLP 160 Stat, SLP underdrive pulley, Hurst, Eibach lower spring, BMR lower control arms, BMR toe rods, Razzi body kit and Borla axle back. Tuned by me

HPT.