cutting cataletic converter

[xjordie]

I have a 99 xj thats a beast and i want to make it louder. I already have flowmaster single chamber race mufflers and its loud already. I Wasn't planning on putting a header on but would you suggest cutting the cat and running just the muffler. Would it loose horespower or torque? I want it loud as hell.
Thanks

 

[dizzymac]

Is this your DD? What about state vehicle inspection?

 

[Shomsky462]

i dont have a muffler right now. but from what i have heard and what it seems like on mine that you lose a small bit of horsespower because there is no pressure in anything, ive also heard that tubing size and exhaust is critical on the 4.0 HO. all i know is that mine is too loud ohh and if you do cut off the cat then your exhaust pipes will rattle around like crazy. it makes like a clanging metal vibration sound at idle, i can marely hear the lady at the drive though over the noise. i guess if you secured it, it would be ok but yeah its really really loud when you dont have a muffler, doesnt sound like it in the car but so many people ask me why my car is so damn loud.

 

[azdesertrhino]

I want it loud as hell.
Thanks

Why, just to annoy the hell out of people?:gag:

 

[wilcharl]

breaking the law breaking the law.. bad boyz bad boyz what you gonna do .. what you gonna do when they come for you

 

[dynamite44]

if you get caught without a cat, the fine is 5 grand per catalytic converter.

EPA's a bitch!

you may have trouble finding an exhaust shop to fab up a pipe (if yours is flange mount, requiring flanges welded on the ends) for your application. i know you've gotta pay big money around here to get that done, and its under the table, no receipt.

 

[Rev Den]

Would it loose horespower or torque?

Yup

Rev

 

[shortxjdoug]

why do you not want a cat anyway. you don't need to be a greenie to worry about air quality. you might just say that its just one car without a cat, but what if i did it and then the next guy and so on, then you got a lot of bad air, now i'll get off my soap box

 

[ROBZ95Xj]

I have a 99 xj thats a beast and i want to make it louder. I already have flowmaster single chamber race mufflers and its loud already. I Wasn't planning on putting a header on but would you suggest cutting the cat and running just the muffler. Would it loose horespower or torque? I want it loud as hell.
Thanks

runnin a flowmaster with a gutted cat makes it to loud, the cops will be on you like flies on sh*t

 

[HilltopXJ]

Not give any bad ideas, but before I got a new exhaust I ran with a flowmaster and gutted cat. Wasnt that loud.(not even close to a diesel truck) and it even passed state vehicle inspection.

 

[DenLip]

I want it loud as hell.

Taking the "pleasant" out of "Pleasanton"?

 

[Rick Anderson]

I'm a noob when it comes to the XJ, but have a lot of experience on other cars. The Cat in most modern cars is pretty free flowing, removing it seldom gets you anything other than extra noise. Guys dynoed a Neon's after removing the CAT and actually lost 1 HP. Don't know about the XJ, but I would suspect the same would be the case, the CAT takes almost none, or even none at all, power out of the motor.

Yes, if you just want extra noise, than yea, I guess it will work, but its just not worth it. Most likely your going to have some future problem where you going to wish you had not gutted or replaced the CAT with a straight pipe. If you get nothing but a lot of attention grabbing noise, then why do it?

 

[BSD]

would you suggest cutting the cat and running just the muffler. Would it loose horespower or torque? I want it loud as hell.
Thanks

Here we go again.

 

[jeepsrock]

On a 99 you probably have a few if not 4 oxygen sensors that monitor before and after conditions of your cat(s). By removing not only are you gonna trip your check engine light but your jeep will most likely operate at reduced power output. Your ECU will try to compensate and you will lose power. YOu will additionally lose power due to the fact you will have no backpressure.

If you want a loud jeep there are many options you have, various mufflers, various loud catalytic converters and diff cat back systems.

pete

 

[dizzymac]

Ahhhh.....shortxj.....I certainly hope that soap box only had phosphate free soap in it.....lol

 

[89BlackXJ]

Alright.....at the expense of sounding like a comlete nerd heres my two cents.....the Cat contains platinum which is uses as a catylist in the bonds of carbon monoxide/carbon dioxide. It takes the CO (carbon monoxide) and the platinum in the CAT allows another bond of oxygen to form with the carbon forming CO2 (carbon dioxide) through oxidation. CO2 is a very stable and unharmful product unlike CO which is a deadly gas. This means that by removing the CAT.....firing up for jeep in your garage...not a good idea anymore...and if anycarbon monoxide leaks into you cab via open doors and leaking seals.....then you could easily pass out or become light headed while driving. The carbon monoxide steals the oxygen from your blood turning itself into CO2...and your body no longer has oxygen for your brain.
Now that i have lost all of your respect from remembering all my chemistry...i will stop talking.

 

[RockTracXJ]

Alright.....at the expense of sounding like a comlete nerd heres my two cents.....the Cat contains platinum which is uses as a catylist in the bonds of carbon monoxide/carbon dioxide. It takes the CO (carbon monoxide) and the platinum in the CAT allows another bond of oxygen to form with the carbon forming CO2 (carbon dioxide) through oxidation. CO2 is a very stable and unharmful product unlike CO which is a deadly gas. This means that by removing the CAT.....firing up for jeep in your garage...not a good idea anymore...and if anycarbon monoxide leaks into you cab via open doors and leaking seals.....then you could easily pass out or become light headed while driving. The carbon monoxide steals the oxygen from your blood turning itself into CO2...and your body no longer has oxygen for your brain.
Now that i have lost all of your respect from remembering all my chemistry...i will stop talking.

Uh, I would saying firing up your Jeep in a (closed) garage isn't a good idea whether you have a cat or not.

 

[Rick Anderson]

CO2 and H2O is the byproduct of COMPLETE combustion of the gasoline. Unfortunately, nothing is perfect, and you often don't get PERFECT OR COMPLETE Combustion, and you get additional byproducts, like CO, HC, HxCx(Many different combinations of Hydrogen and Carbon, refered to as just HC) and NOx(Many different combinations of Nitrogen and Oxygen, refered to as NOx.

The more efficient your motor is running, the less CO it will make, thus the less it will need the CAT. Most modern, computer controlled cars, once they are warmed up, would make very little CO. Perhaps still enough to kill you if you let the motor run long enough enclosed in the garage, it might take hours though if you car is a 90 or later and running well.

Everything you said about CO2 is true, except that it is poisounious as well. The level of CO2 gets too high, it will form acids in the blood that poision you.

I put the removal of the CAT, especially just for noise, in the same category as painting your headlights black, just to look cool, even if you never drive at night. One day your going to need the headlights and your going to be sorry you painted them black, even though you thought you'd never need them.

 

[jeepguy97]

IMO anything more than a flowmaster on a 4.0 makes it sound like a neon with a fart can.

 

[Ben H]

if you just want it louder then get some race readies.