I decided to replace my cat with a piece of 3" tubing. I have a single Borla cat-back installed already. I made up several flanges out of 3/8" plate, bought 2 exhaust gaskets form Ford and went to work. After a couple hours I had the cat removed and the tubing installed. All I can say is you wouldn't believe the noise the cat removes. With no cat, I have a nice rumble/gurgle at idle. So far, so good. Hit the gas and it really screams. On the road up to 2400rpms, it is OK. 2400-3500 rpms it raps out so loud it's actually imbarasing! Sounds terrible! Like a really sick outboard motor. Seat of the pants dyno says maybe a bit more power or is it the extra noise? Hard to tell. Fuel economy seemed to stay the same. I put the cat back on this afternoon. No more noise! Seemed to drive the same. In my opinion, the cat really doesn't rob any power and keeps our V10's civilized. I would say this mod isn't worth it.

 

I'm surprised removing the cat and driving it didn't set off any ck engine lites.

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2k F250 CC SWB 6 speed 4x2 Diesel XLT Super Duty, Woodland Green
Power Mirrors, 3.73 LS, Captains Chairs, ARE tonneau top, rear privacy glass
TT Pkg, Class IV hitch, sliding rear window, running boards, mud flaps
265/75/16 AS OWL tires, am/fm/cassette/cd, rechargable MagLite
Clarion APA 5240 amp, Memphis speakers:Components front, 5x7 rear, 10"sub
SuperChip, Stepshields, Ventshields on windows, rubber bed mat
rugged liner bedliner on tailgate, quick disconnect jumper cables
unaFORDable (decal on tailgate) Western Diesel Turbo Brake (whoa boy)
Finally gauges!!: Pyrometer & Boost on the A-Pillar mount

 

I was worried about that too. One of the reasons I tried. My truck does not have an O2 sensor after the cat so I think that's why it didn't.