Punching out cats.

NeVeRLiFt said:

Gutting your cat's will make your car louder... if you think it sounds like **** then you must have some bad mufflers

The muffler controls the tone and sound your exhaust makes. The cats just sorta quieting it down. Sorta like putting your hand over your mouth and trying to hollar or breath.

Every car I have owned has ran better and gotten better MPG after removing or gutting the cats.

Click to expand...

Louder....Yes
Better....NO!

As I stated before....gutting the cats amplifies the exhaust not, but also amplifies that oh so annoying sound of each exhaust pulse as it exits the collector (mimicking that of an exhaust leak) and also increases the oh so famous drone created when making exhaust modifications. The Cats on the stock system aren't just there for smog protection, they're also there to act as resonators to keep drone to a minimum. Getting rid of them increases the resonance volume. It’s got nothing to do with you after cat system. Even removing the Cats on a stock system increases the drone. It’s not speculation, just plain old fact. One way of reducing this is to replace the stock H-pipe with a larger diameter O/R unit. It won’t do much for the drone, but it will at least cure the tiny sound otherwise produced by hollow cats. An O/R X-pipe does a better job still of controlling noise, not by reducing it, but by moving the exhaust reverberation further up in RPM, to the point where it’s mostly drowned out at highway speeds.

Also, mufflers have very little to do with an exhaust systems "tone". They're able to alter or muffle volume slightly, but exhaust tone is only able to be changed by a few limiting factors.

1. Changes in the engine whether it be displacement, cam, head, etc
2. Change in exhaust pipe diameter
3. Changes in exhaust over all length
4. Changes in crossover location

Besides, I said nothing of gutting cats hurting power production or fuel economy. Reducing backpressure to an extent will do nothing but help in these matters. But is still sounds like @ss compared to a proper O/R midpipe!