Hi all,

I want to delete the 3rd cat and put a piece of straight pipe in its place on my 2004 SC430. I like a more aggressive sound from the V8, and have heard another SC430 with a 3rd cat delete and liked it.

My question is, if the 3rd cat is deleted and replaced with a straight pipe, will i get the check engine light? I've heard that there are no o2 sensors in the 3rd cat so technically it shouldn't trigger the CEL, but some people still report that the CEL lights up.

A reputable muffler shop nearby will be performing the work for me, so there is no doubt that it will be done professionally.

Any info would be appreciated.

 

If the CEL lights up from doing this, it probably means that the third cat is monitored.

I don't think it is, but that would certainly cause reason for concern. A third cat delete is a nice way to gain more engine sound from your V8, but cold start emissions/smell will be somewhat compromised.

 

If anyone knows for sure if the 3rd cat is monitored, I'd greatly appreciate it. If it is then i will probably not go ahead with it, as my car won't pass inspection with the CEL on.

 

The 3rd cat is not monitored , it will not affect emissions, get rid of the resonators as well

 

Wouldn't just removing the resonators give the same effect?

 

Yes the third cat does affect emission inspection.

Dont remove your resonators that's just awful advice. It's going to sound like garbage unless you at least replace them with some high flows.

 

Really ? you think mine sounds like garbage ?

 

It sounds good but you can tell its unresonated.. you need to understand what your resonators do first before you go suggesting that other people start removing them. They are an important part of your exhaust system.

if you're going after good sound, the factory resonators could be removed, but be sure to replace them with an aftermarket such as Vibrant or MBRP

 

yeah ok , next you will be telling me it drones when im driving it.

 

you better listen to Moisture because he just joined club lexus last month, already has over 500 posts and who doesn’t even own an SC430, according to his title. And then Moisture comes here to slam a member who contributes and helps others. Lawler999 has an awesome sounding SC430.

Moisture, we get along very well and certainly love new members. You might receive a better reception if you are respectful and earn some respect before you come in here with your guns in full auto.
i also noticed you were born in 1906...Great Year for Earthquakes and Fires.

 

Dang lawler999, that is one mean *** sounding SC430. Makes we want to GTFO your way if I hear you coming.

Awesome,

Ian B

 

see post 21-22 in this thread
https://www.clublexus.com/forums/sc4...magnaflow.html

 

haahahaha. Thanks for the laugh.

In all honesty I was just trying to be constructive. Resonators create a good type of "backpressure" within your exhaust system, if you will. (They resonate your exhaust flow which is a form of turbulence that is an important part of a good exhaust system) hence which is why you never want to go fully unresonated. USUALLY it doesnt sound good, in his case it does.

There are key differences between a loud, good sound, and proper flowing exhaust. Theres much more to it then the sound it emits, such as the shape/bends in the piping, whether the cats are inside or after the exhaust manifold, the design of the muffler ( which even assists with airflow and air pressure underneath the vehicle... etc. Etc.

Not to mention, resonators also filter out alot of unwanted droning and frequencies you may otherwise encounter in an exhaust system. The only time it would ever be acceptable to go unresonated is If you are installing an x-pipe ( if applicable.) Otherwise you're just messing up your exhaust flow and losing a bit of power while *usually* emitting an awful sound.

The problem is, factory resonators are usually way too big and restrictive because they are designed for normal drivers.

 

Hey Guys, thanks for all the information. If the 3rd cat is not monitored and the CEL won't show up, then i'm going to get it removed tomorrow. Here in Australia, we don't have emission inspections - just the road-worthiness of the vehicle is assessed (i.e. tyres, engine, steering, electrical components etc). That's why i was worried that if the CEL lights up, then the inspection won't be passed as the inspector will clearly know something is wrong with the vehicle.

 

And Lawler, that is one mean sounding exhaust - i have to admit! Unfortunately, i probably won't be able to get something like yours though i absolutely adore it, as the police in my area are very strict on vehicle noise and exhausts - especially on young drivers like myself. Don't want to get slapped with an infringement!