Cat Outta The Bag

BISavage

champion rider
Joined
Oct 8, 2020
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2,382
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Unspoken Origins
401 Specifically 18-19
When using all methods for tuning, does a decat actually improve "performance" on a 401 from 18 to 19?

For specifically the years 18-19, looking at the charts have the feeling it would makes the bottom end weak, the top end slow, and somewhere a sweat spot with crazy torque.

On older 390s it was proven to jack the stats, and on newer 401s / all 701s it jacks the stats... I am wondering why they seem to be so popular.

Maybe there is a difference between Arrow/Leo/Rtamo/Geo/Coober/Werkes?

Anyone actually have experience on a track or with tuning one out?
 
They are popular because people associate more noise with more power.
And anything that has to do with emission control eats power.
What most people forget or are just not willing to spend on is getting the fuelling adjusted.
 
Very, very few people dyno before and after...
That said, I don't mind the cat, but that resonator box is really ugly, imo.
 
They are popular because people associate more noise with more power.
And anything that has to do with emission control eats power.
What most people forget or are just not willing to spend on is getting the fuelling adjusted.

I agree to some extent, for some vehicles.

For these bikes, I would be imagine that the design of the cat causes only a negligible impact to weight.

After having it in my hand, this specific cat for this specific model seems as though it would improve flow as opposed to restrict it.

Of course heat would be an interesting point, with the cat, engine operating temp is surely achieved sooner, while heat soak is moet likely increased in stop and go situations.
 
I would expect that from the feeling, cat vs no-cat has the similar performance impact as non-powerbomb vs powerbomb.
 
would having a powertronic or any other ECU help address the fueling issue with the popular decat mod? the previous owner removed the cat and added a slip on
 
My understanding, if you either open the lid, or remove the cat, or both, you need to add fuel via map or piggyback to not risk dangers for the engine.

Slip-on pipe & drop-on filter are ok as the cat and airbox should be controlling the airflow.

I have heard the full setup makes the most power and arguably the best noise.

I would like to know if there is experiance with the full setup minus decat, or with a specific decat vs. other decat options.
 
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