2003-04 Mercury Marauder headers and 2-1/2" catted pipes. 1 5/8" primary tubes with 3" OD collectors. Long tube design makes great power and mid range torque. 3/8" s/s CNC laser cut flanges are port matched to the cylinder head for optimal flow and maximum performance. Designed for use with factory exhaust system. 2003-04 Mercury Marauder headers and 2-1/2" catted pipes. 1 5/8" primary tubes with 3" collectors. 3/8" thick flanges are port matched to the cylinder head for optimal flow and maximum performance. Designed for use with factory exhaust. 2003 thru 2004 Mercury Marauder 4.6L