PoleVaulter95

got this crazy idea of removing my cat (live in oklahoma no emissions testing). i want to have a straight pipe made that i can just bolt right in place of the cat. im hoping this will give me a little more power. has anyone done this before? good or bad? and how do you get those bolts off. am i going to have to cut them? thanks for any advice

TNRabbit

Been done many, many times by folks all over the U.S. on multiple types of vehicles. You would probably only realized a very slight increase in power/mileage (5% max unless your cat is blocked), but would do away with a source of potential blockage & expense. Any good exhaust shop will be able to do this, just make sure they don't screw up your O2 sensor (have them remove it first) from the heat if they weld the pipe in. I'd recommend retaining the bolt-in option in case the rear exhaust goes bad so you don't have to cut & re-weld or replace the entire system.

Soak all the bolts down with a rust buster (liquid wrench, etc.) for a couple of days before you try to bust them off.

PoleVaulter95

Thanks for the advise ill be sure to post my results from ditching the cat

Red3.slow

if you have the stock muffler/all stock. I would advise against cutting off the cat. I saw no milage increase same/ slightly less power and torque. so just beware.

TNRabbit

Red: You know, I hadn't thought about it, but the O2 sensor may actually use the backpressure created by the cat to help "push" the exhaust stream into the sensor...?? Perhaps that is the reason for your perceived slight decrease in power...

PoleVaulter95

Red how excatly did you go about cutting off your cat? I noticed it says you have a custom exhuast. did you do the cat removal before or after all this. did you just un-bolt it and have a 2.25" pipe made to bolt in place of it. or did you cut it out and have a pipe welded in? my bolts seem to be completly seized on there. im comtemplating just cutting the bolts off and getting new ones. im new to this whole modification scene so any advice is appreciated.

Red3.slow

I haddn't thought about the o2 sensor using back pressure. Hmm that's an interesting idea. I'm throwing an EGR trouble code but nothing with the o2.

I literally cut the cat out and welded in a stock size tube. So basicly what i'm running in about manifold back 2.25 inch tubing right in to a glass pack.

My bolts where rusted as well. I tryed all kinda of rust eatters, lubes, ect. But the saw came out.

Oh and befor someone says anything; I have plans of overhauling the exaust. I'm not trying to get the attention/distroying peoples ear drums and making small children cry.


If i where to do this again I would try my hardest not to just cut it out.


One last edit. Though I think cutting the cat out isn't very benificial the 3.0 will get up and go. She does have as much power as I need 85 to 90 percent of the time. Which is better then most of the other's I've been in.

tjyota

I had the same idea, removing the cat to get some more power or better mpg, either one, lol, i never got around to do it until my cat got stolen, thats right STOLEN, the sob's left the bolts liying right there on the pavement, so anyways i took it too a muffler shop and had them instal a piece of pipe and it ran good for a while, and it made a cool sound that is until it bustes my muffler(it was pretty old to begin with) and then i noticed a lot less power, so back i wetn, only to a different muffler shop, they told me that since i only had a straight piece of pipe the muffler was getting the gases full on, they recomened getting a resonator( bassically a dual pipe with ridges inside of it) and a new muffler, about 60 bucks parts and labor (i live in mexico).

everything was ok for about two weeks but im feeling a loss of power again, im wondering if its the o2 sensor, if so, witch one, went to the autozone to get a quote end they asked me witch one i wanted, the one after o before the cat O_o, either way they were about 100 bucks a piece.

any sugestions?

PoleVaulter95

i dont have any suggestions yet because i havent done this yet. im just curious though what new muffler did u have put in and did u go with the normal 2.25" pipe i would like to know what your problem is when u get it fixed thanks for the input

cootees

Check ebay for the 02 sensor.. or search around online for one. Stay with denso or ngk.

First of all, just because yo udo not have emissions testing yet does not mean that it is legal in your state to run without a cat. You could find out next time you want to get it inspected you will fail because of no cat. So check your state laws regarding this issue before even considering it.

Secondly, Removing your cat will mess with your 02 sensor(s) causing you to possibly throw a code. Have you ever considered that the cat is there for more then one reason? Thats right it's primary job is to control the emissions BUT the vehicle was designed to work in conjunction with the cat. Like I said before removing it could cause your check engine light to come on and cause the vehicle to start running improperly which could even then result to engine failure.

Replace it with a high flow cat if you want. Every Magnaflow cat is considered high flow compared to o.e. Hell get one of the new Magnaflow metallic cats and that is a serious high flow converter. Which they should be available any day now.

(for those of you who know some about performance cats then this should intrigue you.)
I recently had a customer call me looking for a obdII compliant cat that would flow much better than random technologies converters. Now a bit of background: Random Technologies is big in the race scene claiming they are the highest flowing converter... Random Tech. is not even obdII certified but they do not tell you this. I called random tech. one day to ask them how they ran the benchmark test on the cat... in how much water, the inlet/outlet size cat they used.. ect.. I then called my magnaflow rep and had him do the same test to one of their metallic cats using the exact same specifications that random used to test theirs. To make a long story short. The Magnaflow metallic cat blew the random technologies cat away.

PoleVaulter95

Thanks for the suggestions cootees im going to look into the magnaflow cat. are you running one yourself? where do u think i can find a good deal on one of those

LOCKnGO

cootees

Down here in Americas penis (FLORIDA) we have no emissions testing. I bought the Downey exaust system and never installed the cat and ever since my exaust SINKS! And I saw a loss of power not so much in the low end but def at the top. I put on a reduced it to a 2" tip trying to get some back pressure.
Magnaflo make some of the best exaust systems out there If you have the $$ get it you can't go wrong.

AH64ID

Did it, wont ever do it again.

There was NO increase in pwr/mileage... There was an increase in noise and stink... So bad that I couldn't drive with my rear window down anymore...

Even in states w/out emission testing the fine is HUGE for going w/out a cat. Dont quote me but I think its something like 25K in washington....

If you want a better flow get a hi-flow cat. The one from carsound in 55 bucks for a universal weld on or a few more bucks for a direct fit... Hi-flow and no stink and no fine...

I currently run the 53005 cat in my P/U

Elton

with a 3.0 cutting the cat off is pointless just go buy one and have it welded on with a new exhaust