These baffles are great for Street Rods, Hot Rods and Rat Rods with Zoomie or Funny Car style headers. The kit comes with 6"” long baffles, that bolt in. The baffles are wrapped with high temp, long lasting, stainless muffler packing. SB Chevy application with “zoomie Funny Car” style headers yielded a 10 decibel reduction in sound volume, and still had a deep aggressive hot rod rumble. Sold in kit of 8. Remember to choose your size from the drop down box above. Order according to the outside diameter of your pipe. Example: Small Block Chevy / 671 Blower / Sanderson Zoomie Headers / 500HP Before Idle: 85-87 Decibels After: Idle: 75 Decibels 2000 RPM: 95-98 Decibels 2000 RPM: 85 Decibels. Also Sound clip: (32 Ford) Blown Big Block Chevy. Check out this link: http://classicalgasenterprises.magnify.net/video/1932-Ford-Custom-Coupe-1001-5/theater#theater_title