JG*

Hey everyone,

Ive tried searching up info on high-flow cats and cant find much.

Does anyone know if, with high-flow cats, it causes CELs or any other complications?


If anyone has more info can you post a URL or hit me back !

Basically, just looking to increase HP and torque. Im doing a custom air intake, with the meisterschaft cat back and an ECU tune but, i NEED more flow through the cat area to get more hp!

thanks everyone.

sagar526

Are you looking to remove the cats in front of the resonator or further up than that? If its in front of the resonator, there are no sensors around that and you can weld in a test pipe there without worrying about CEL warnings.

jbt56

Having spent much of the past twenty years in the performance exhaust industry, I can say with some authority- your OE cats are pretty much the best out there for your car. ALL modern cats are 'high flow'. 'Low flow' cats have not been available for many years, now.

Car companies use the best, most over-engineered cats available for a few reasons. One, they can afford it. Good cats are expensive to build. Two, they have strict warranty periods, demanded by governments worldwide. OE cats (and other emissions parts) are required to be warranted for at least 5 years/50,000 miles, with some going to 10/100k. The last thing Mercedes or any other company wants is to be replacing parts under warranty.
Your general aftermarket 'high flow' cats have what's known as a 200-cell count core. This makes for great airflow, but also makes for a horribly inefficient converter. These often trigger MILs, because there just isn't enough precious metal surface area for the cat to function. Some of the more expensive aftermarket units are 400-cell. These are equal in count to most domestic OE cats, but their build quality is to a much lower standard. German cars like our MBs use up to 1200-cell cats, which provide incredible airflow, but also work amazingly well in their job performance. The OE cats are also designed for the life of the car, taking into account the many types of driving the car will see.

The myth of the OE 'low flow' cat is just that. Thirty years or so ago, it was true, but again, ALL OE cats are very high performance and have been for a couple of decades. The only time they MIGHT be overwhelmed is when one is at minimum doubling the engine's power.

I hope this helps some, even though it's opposite what most cat company marketing says. Heck, I used to write some of that stuff!

JG*

Whoa! Thanks that answered my questions lol!!

Looks like im not going to be changing my cats..

I should have just got the AMG! All problems solved with that model hahahha!