I have removed my muffler already and I was wondering if I cut off the cats but left the O2 sensors would this still be fine on my 1999 F150 5.4L V8
Im not worried about any tickets but I wasn't for sure if this would be bad on my motor since I would be leaving the sensors?
Can someone help me ?!

 

NO!! do not do this to your truck. if you must remove your cats, at least replace them with a set of high flows. Unless your doing some kind of crazy high performance with crazy tuning set up you wont gain anything by removing your cats and you will most likely shorten the life of your engine. Oh and i'm pretty sure your milage will drop.

 

I was just wanting A louder noise out of it but I thought if the 02 sensors were still in the piping then everything would be read fine on the computer and wouldnt it be better because with the cats being gone wouldnt it be alot less restriction

 

removing the cats does get rid of a lot of restriction, but in this case, this is a bad thing. The restriction of the catalytic converters causes what is called back pressure, and when you eliminate this, your low end grunt seriously tanks.

the O2 sensors tell the computer how the engine is performing and how much fuel to send to the injectors. there is a set before the cats, and behind the cats, and they work together in conjunction with the catalytic converters to ensure your motor is running properly. and a properly running engine is more efficient, and more reliable. I am sure someone else can and will chime in with more details about all of this, but this is a decent outline of what is going on.

bottom line, completely eliminating your cats, is probably not the best idea in the world, but it has and can be done, but under the right circumstances.

 

If you're...

go to Radio Shack, get a couple of microphones, a PA amplifier & some head phones. Set up the mikes so you can amplify the sound that's there thru headphones. Then you can turn up the volume until your ears bleed w/o becoming a nuisance to others.

 

Only way to do it and have it work properly is to remove all 4 stock cats and replace them with two high flow cats. One on each side.
Putting the 02s back in place with one in front of the cat and one behind the cat.
This will free up the flow and increase the volume significantly!

 

How much is a high flow cat and what brand should I go with?

 

I run Bassani cats but there very expensive.
Look on ebay for Magnaflow high flow cats.
You should be able to find them for about 50 to 80 bucks a piece.
http://www.ebay.com/sch/i.html?_nkw=....c0.m270.l1313

Some guys get away with just cutting off the to back cats and welding a piece of pipe back in there place. But be sure to put the back 02s sensors back in as close to the cat as possible.
Might be a little cheaper for ya that way and will increase your volume also.

 

Go on YouTube I was just on there and there's a 2002 screw with the 5.4. The guy has all cats removed and has flowmasters dumped under the truck. It sounds pretty bad ***.

 

I guess I will buy a high flow cat but it might take some time to get em

 

Can you remove the cats without problems? Probably. Should you, maybe not.

Removing them will make the truck a little louder. However, it will also make your truck more sensitive to catalyst degradation, and your CEL may come of for catalyst inefficiency. If you want to try it, you just have to take the risk of a light coming on. Either way, there is no risk of engine damage.

I would personally opt for high flow cats, but before doing that, you need to do some research to understand what a high flow cat is, otherwise you will get ripped of with something that is no better than the OEM unit, or in some cases inferior in terms of flow and performance.

Most cats sold as high flow cats on eBay, Amazon, Summit, Jegs, etc. are ordinary 400 cpi ceramic catalysts of the same type and density as OEM. Their flow potential becomes a function of case design, cross section, and length. Most OEM are well engineered, so there will be little or no improvement. In fact, many OEM cats have a larger cross section, larger cross section means more flow potential, and that can mean that some OEM cats will outflow the smaller aftermarket counterparts. Don't assume that just it has a performance oriented brand name that the converter is a high flow cat. Cats sold under Magnaflow, Dynomax, Cherrybomb, and other performance labels are usually just ordinary cats. This can be confirmed by the price tags, they cost about the same as ordinary cats ($40-$120).

Real high flow cats have design features to increase flow without compromising their efficiency. They can be made from either ceramic or metal substrates, and will have cell densities of less than 400 cpi, typically 300, 200, and sometimes even 100 cpi. The lower the density, the high the flow. However, the lower the density, the less efficient the converter is, and the more likely CEL are to be triggered.

Within the performance converter world, very few are offered in direct fit bolt in configurations, almost all direct fit parts use ordinary 400 cpi ceramics. Also, the quality of high performance cats is varied. Just because it is a well known brand name does not mean it is a good converter. It might flow well, but if it does not perform its primary function as a catalyst, it is nothing more than an expensive alternative to a straight pipe. I know some will swear by Magnaflow in specific (mostly because the name is so popular), but my experience has taught me that Magnaflows real high flow cats do not have enough or the right types of precious metals to meet the requirements of most 1996 and newer vehicles. This is confirmed by their low price, they can sometimes be had for as little as $120. They use roughly the same loading density as a regular Magnaflow cat, but with less than half the active surface area. I would only use those types of converters on early OBD-II and older.

What I use these days for those who want more sound and performance with the CEL is these.Untitled Page

Sure they cost a little more, but I have yet to have one set a CEL, and I use them on some pretty new vehicles at times (I've used them on as new as 2010 models without issues) They sound they produce is pretty impressive. Loud, deep, and throaty, like a straight pipe, but smoother. From there, its a matter of what muffler you use. Performance gains? Well, that depends on a lot of factors. These won't get in your way, so you will produce as much power as your engine can. If you add real performance parts, like superchargers or turbochargers, they will already be up to the task. I would say your HP limit is probably around 400 hp per bank. I have used these on STis that were afterwards dyno tested to produce over 350 hp at the wheels.

From a performance standpoint, most 200 cpi metal cats are going to be the same regardless of brand. Their flow ratings are similar to straight pipes, maybe just a little lower, but the difference is ignorable. For reasons I cannot fully prove of claim, some systems with high flow cats have more performance that straight pipes. It is probably related to the thermal induction cats produce combined with factory cams that are designed to factor in a cats presence.

The primary difference between different brands of high performance cats is loading. The cheaper and more popular brands often use lower grade metals like palladium, instead of blends containing higher grade metals like platinum and iridium. Cheaper products also tend to use less of the material, with cheap products containing between 9 - 15 grams per cubic foot, and higher quality products containing between 18 - 30 grams per cubic foot. Because cheaper products contain less material, and the cell densities are lower than standard cats, the efficiency may not be sufficient to keep the CEL off, especially after degradation of time is taken into consideration. Since the performance differences between brands are ignorable, efficiency should be the primary deciding factor. Using more of higher grade materials drives up the price, so a general rule, better high flow cats will cost more.

A lot of this depends on what you are trying to accomplish and how much you are willing to spend.

So to sum up. Yes, you can remove two of your cats, with possible risks of a CEL, with an increase in sound, but little or no performance gains. Replacing them with cheap standard cats will only make your wallet lighter unless your originals were already partially plugged and in need of replacement. High performance cats are quite expensive, but do deliver significant increases in sound and can support however much power your setup is capable. They are more worthwhile if used with supporting mods.

 

so there rly isnt any risk of damage and the prob, like the enigine

 

I think he has misstated that!
The truck will not get proper readings to the computer to adjust the fuel.
Will it do any major engine damage, probably not but it wont run properly unless you get some custom tuning to eliminate the function of the 02 sensors so that they no longer adjust your fuel tables.

Oh, and the Bassani cats I run were about 200 bucks a piece.

 

Just as an FYI seeing as you are showing as being from WV you should be aware that even though the state of West Virginia does not have a tailpipe emissions testing, the state does require the catalytic converters to be there as part of getting the state inspection sticker. Also, I highly doubt you will be able to find a reputable shop that would be willing to do it on this new of a truck. If it was on something from the 80s that was being built off road only or had antique plates then you wouldn't have to worry about the inspection sticker. Plus, like was said earlier in this thread these engines have way to many computers controlling them and if you remove the cats you'll confuse the living daylights out of the computer and it's more of a pain than it's worth.

 

I was wondering if these high flow cats would be good to buy and use on my truck http://www.ebay.com/itm/OBX-METALIC-...ht_2027wt_1110