Justin251

When I bought my fx4 it already had the flowmaster on it.

It's a single then y to dual tips. It sounds ok. I'm not a flowmaster fan. My point is this.

While changing my oil the other day I could only count two actual cats. I know what cats look like. But aren't these trucks supposed to have 4?

I couldn't see any pre-cats like what my 2000 mustang had. They looked drastically different from the actual cats.

On my truck you can see the two cats and they are pretty much just bolted straight to the manifolds.

It's this correct? Doesn't really change anything I'm still going with a custom magnaflow later on.

1wheel_up

i do believe my 04 5.4 only has 2 cats also i also have a flowmaster (sido) 40 series i love how it sounds not to loud not to quiet. i dono what series yours has but if its a 50 or somethin it would be quieter.

Justin251

I think it's a 40. I've just never liked flowmaster. Also, some of them flow worse than stock mufflers.

Mod (Ret.)

There was a change pertaining to cats sometime in the 04 to 08 years; some had 4, and then Ford switched to 2 for the 5.4 equipped engines. I don't recall the year this changed, but it can be found with the search.

Justin251

Well, that's just the thing. It looks like all factory exhaust from the flowmaster forward.

So it probably only came with two cats.

60DRB

Probably. I think my 4.6 has two cats as you describe, and 4 O2 sensors.

Justin251

Yeah, the rear two just check that the cats are working I believe.

LovetheTide

Early 05 trucks had 4 cats, later 05 trucks have 2. If you have 4 cats you can cut off the rear two without causing any problems such as codes coming up. This will increase the sound levels of your exhaust.

garyv350

I have an 04 5.4. It has a single chamber flowmaster on it with sido and just dumps out the muffler. I like exhaust rumble but the drone in the cab is way too much. My question is what size is the stoke exhaust pipe in? Not sure if it's 2.25 or 2.5 inches. I am looking for a quieter sound with still some low rumble. Any help or suggestions would be great. Just without the drone. Thanks.

Justin251

Running out the back helps. I'm going with a magnaflow bullet type straight through muffler.

Possibly a canister type design but I am unsure.