The front cats are VERY small, smaller than highflows. Unless they're clogged, they aren't killing the sound/volume.

EDIT: Just noticed you had an '04. The later model F150's have larger front cats than the older ones... Semi-ignore my post. LOL.

 

random question while we are on cats, my 06 doesnt have the usually 4 cat set up that my 05 and 97 had. it just has two cats with the o2 sensor in the cat. so can i get highflows with that o2 port and not trip the light, and still pass the emissions? i have cutouts and its not loud enough so im goin to put headers on regardless.

 

I have the maggie cats with the O2 bungs already in them and no CEL as of yet, been running that way for almost one year now.

 

The cats with the O2 mounts in then are #94136.