every post i look at some people say they have cats and others say they have reonators. what does a resonator look like and what does a cat look like. im getting ready to stack my 98 and have to have it E-Checked so i need to know if it is a cat or a resonator. mine is rectangular and angled at the front

 

Cats are on the 12 valves, resonators on 24s

 

thank you for clearing that up for me

 

What exactly is a resonator and why would you want your exhaust to resonate in the first place?

 

You'd want a resonator to keep it quiet. Helps a bunch against the dreaded drone.

AlpineRAM

 

So a resonator is actually an anti-resonator. Just like a sway bar is really an anti-sway bar.

 

And a shock is actually a swing absorber

 

A little better example would be.....Both are a big can mounted somewhere before the muffler. A cat is a can filled with some sort of honeycomb material, usually ceramic, acting like a filter. It catches the soot from the engine which will then burn off as the cat heats up. Results in cleaner exhaust. A resonator is a can usually mounted before the muffler that is empty, absolutely nothing in it. Just a big hollow space. It gives the sound a place to bounce around in, toning the exhaust note down a little. This is a resonator: http://shop.airflowonline.com/Mercha...ategory_Code=R

 

Here's the scoop on the Resonator:

Once upon a time, galaxy far far away, etc,
Dodge had an exhaust system for the 12 valve Cummins engine that included a Catalytic Converter.
Mr. Cummins came out with a 24 valve engine that met the strict EPA's (Environmental Polution Agency) emissions guidlines without needing the CAT.
Dodge remove the CAT, but found the exhaust system resonated horribly at certain RPMS (annoying reverberating noise).
The found that if they put a fake CAT back into the system, it fixed this noise.

If you take a good look at the Resonator, you'll see it's just a mini flow through muffler.

Then Mr Cummins put an even better, new and improved injection system for their 24 valve engine,
but Mr. EPA wasn't happy, so the Catalytic Converter was put back in for 2004.5.


phox