I Just Installed My Turbo Back 4 Inch Exhaust On My 2006 6l. And I Am Surprised How Quiet It Is. I Wasnt Real Sure When I Put Muffler On Which Way It Went As In (inlet And Outlet). The Pics In The Directions Sucked. Any Help Would Be Great. Do I Want The Air Flow To Hit The Ridges Sticking Up Or Flow Over Them?