Has any one put a cat-back exhaust on the LEV Screw ? Mine has what looks like dual cats on each side . Would an exhaust improve performance ? How much ?

 

Most, if not all of the new f-150's are LEV's. My 2000 SuperCab 5.4L 4x4 is for sure. They all have 2 sets of pre-cats+cats on each side right after the header collector.

I installed a new y-pipe and catback for a decent improvement in power and sound.

 

You can go true duals as well. Cut out the Y, come back with madrel bent 304 stainless to a Magnaflow 14486 dual in/ dual out with integral X pipe muffler. Great sound, helps with low to mid because of the X, all stainless and guaranteed for life.

 

Stopped a guy with a nice-sounding Screw in St. Louis today and asked him what kind of mufflers he was running. His surprising answer was, None! Said that he had installed FlowMasters and didn't like the sound so he took them off completely. Said that it is a common practice in the Lake of the Ozarks region of Missouri.

His Screw was not loud but had a nice burbling sound to it. He said that it still passes emissions without the mufflers but might not pass city noise standards at full throttle.

Something to think about!