FYI, those considering removal of your "cats", those little fury annoying things, I had mine "euthenized" today. I have had true duals, 2.5 diameter 40 series flows dumped at the axle, and enjoyed them greatly. But it was time to move on....
I bought some MIL eliminators from Dallas Mustang and had my shop do the deed. My exhaust went from a nice deep mellow sound to just plain mean. The exhaust now sounds very similar a 4.6 gt with an off-road h pipe installed. It is a heck of a sound when that sohc engine winds out!! The only drawback I have noticed is an exhaust smell reminiscent of the old carburator big blocks. So, if you have got the money, get some o2 eliminators, find a shop that looks the other way, and an inspection station who will do the same.....

 

02 eliminators? Where and how much?

 

There are a few on the market, the one that I know of are the Casper Electronics version of O2 eliminators / simulators.

These are for removing the cats, and this is what you would put in the second set, the first set still needs to be installed for A/F feedback to the PCM.

 

Did you notice any changes in power or fuel economy yet? How much did they cost?

 

instead of getting eliminators, cant you just hollow out your cats? Id love to hollow out all 4 of my cats on my 4.6 since i already have straight pipes

 

Green_98, I think that the 02 sensors after the cats will cause the check engine light to come on if they detect that the cats aren't working efficiently, so you need the eliminators to keep the light from coming on. They plug into the sensor and send a constant good reading back to the computer so you don't get a light.

I've been reading up on it. Do a search for MIL Eliminators, you'll find out all kinds of stuff.

 

Two weeks have past since my cats were removed. I purchased the MIL eliminators from Dallas Mustang. They were about 60 dollars carry out. I have had no problems with engine performance. More than anything else, the modification made an immense sound difference!! Now I have everybody wanting to race me. It is a very awesome sound. I live in a dowtown with lots of bridges and buildings for that sound to resonate. My sound is similar to a 4.6 Mustang with an off road h pipe and 40 series flow. At idle there is a nice low "thud" and glug-glug sound.
The engine sounds really mean from 2500 up to 5000 rpms, it just sounds like some sort of really pissed off snarl. When I drop it into 1 to force the engine to downshift as I decelerate, the engine has a very similar gurrgle as when a GT Mustang does the same.
My seat of the pants impression tells me that I think it effected the mid range power more than anything else. Hey, it is an f150, not a Mustang...so I don't expect it to perform as fast as a Gt or Z28, but I can sound like one and dream!! One day a set of I Dynatech (I think) long tube headers will go on it to improve the low end torque where I really need it.
My opinion and gutting the cats...waste of time and money. Yes, it won't pass inspection in emission controlled states/cities, but it will if you can find someone to "look the other way."

 

so let me get this straight. i can remove all 4 of my cats and have the mil eliminators put in and have no problem with the check engine light or anything else?

 

The second set of o2 sensors are for monitoring the convertors to make sure they are still working properly. MIL eliminators trick them. You can also build your own MIL eliminators, I have a schematic at work. I found it on a site about zx2racing. You could probably find it if you search the web.