i have a 2004 f-150 5.4L with a borla cat back system. how will removing the cat effect performance, sound, etc???

 

it will sound a tad louder but i dont even think you would feel a differance in power. the ones ford uses are pretty good with flow.. if anything i would suggest not going to cats and instead use magnaflows high flow cat.

 

unless ur using a chambered muffler i wouldnt recomend messing with cats while it will be louders all OHC engines are designed to use the backpressure from the cats to help compression.. so removing cats and having a free flow muffler u will loose alot of torque especially on the low end

 

Magnaflow 2.50" IN/OUT High Flow Catalytic Converter

"On vehicles with 4 catalytic converters (2 cats on each side of the motor, such as 1997 & up Ford F-150, Expedition, etc.), you only need 2 of these to replace all 4 factory cats."

 

if you go to true duals it gives it alot of power,not as much if you still have the factory y pipe.i've had no cats with factory y and true duals with no cats.i have no muffler now and didn't lose much low end.i pull alot of heavy stuff so i'd know if i lost low end.you have to fix the mil though.put a 1/4 ohm resistor on the downstream o2 sensor signal wire(gray wire on mine i think) and it'll work fine.i've been runnin no cats for 2 years and for the 2 years before that i only had the small ones and mine still runs great.and it is really loud unless you have a muffler,then its just pretty loud.sounds mean as hell though