These things rule! I finally got my Smithys hooked up and man to they sound sweet on my truck. 351W 2bbl heads and intake with a 500 cfm Holley 2bbl The flow direction is turned around from what is indicated , running 2 inch front to rear, 22 inch long Smithys placed about 3 feet back from the headers. The sound is ohh so nice , motorboat burble at slow and cruising speeds , rappy/raspy when you get on it, and a really cool rap and pop on deceleration. I have to give a thumbs up on these mufflers for sure.