Cats or no cats

[Driller6262]

I’ve got cats on my boosted setup, should I remove them for motor longevity or not a big deal? My county doesn’t require emissions for inspections

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[NGOT8R]

I’ve always heard that cats (whether factory or aftermarket) don’t hold up well under boost.

I have LTHs on my 2019 Bullitt and had to switch over to no cats after blowing mine out at the drag strip (naturally aspirated).

https://www.mustang6g.com/forums/th...-broken-weld-on-mid-pipe.191891/#post-3853343

 

[SheepDog]

I’ve got cats on my boosted setup, should I remove them for motor longevity or not a big deal? My county doesn’t require emissions for inspections

Your car must be loud as shit with long tubes, no cats, H pipe and Corsa extremes

 

[Driller6262]

It’s loud as hell with cats. The exhaust was like it is when I bought it. Cats look old and rusted compared to the stainless exhaust. Not sure if they are stock cats or what honestly. I just boosted it recently and didn’t want to hurt the motor by leaving them if I didn’t need too

 

[SheepDog]

It’s loud as hell with cats. The exhaust was like it is when I bought it. Cats look old and rusted compared to the stainless exhaust. Not sure if they are stock cats or what honestly. I just boosted it recently and didn’t want to hurt the motor by leaving them if I didn’t need too

It's only going to get louder with no cats, but as far as needing them - no you dont

 

[Need4SpeedMotors]

It best not to have them, the pressure from the boost ends up breaking them down and can hurt the motor if that material gets sucked back in.

 

[SheepDog]

material gets sucked back in

Material doesn't get sucked back in, the motor gets hurt by excessive backpressure when the cats melt down and block the flow of exhaust

 

[engineermike]

I'm going to muddy the water a bit here.

Yes, the cats fail often and it sucks that we don't have good options here.

However, deleting them isn't as straightforward as it seems.

I dyno'd with and without cats, same day same dyno. Mine made 15 hp more WITH cats than without. This was at 700+ rwhp.

Controlling lamda accurately is a real issue. At wot with low backpressure, you wind up blowing some air through the cylinder which fools the o2 sensors into thinking its lean when it's not. So you're basically guessing at lambda at WOT. Then there's FAOSC, where the PCM logic uses the rear O2's to apply a correction to the fronts. With no cat in place, even with anti-foulers, the rears get an inaccurate signal that results in further inaccuracy in the front widebands. Sure you can turn off FAOSC, or can you?

 

[gone_n_60]

can't help you I'm a dog person myself.

 

[NGOT8R]

Has anyone pulled their exhaust and done an inspection of the pipes to see if there’s an indication of the cats loosening up and starting to fail? When mine failed, I could hear the immediate change in the exhaust note. Pulling the exhaust confirmed what I had suspected. The cat material was being sucked in and blown out during acceleration and deceleration.

Adding Vibrant race mufflers in place of the cats definitely increased the sound of the exhaust note too.

 

[80FoxCoupe]

Has anyone pulled their exhaust and done an inspection of the pipes to see if there’s an indication of the cats loosening up and starting to fail? When mine failed, I could hear the immediate change in the exhaust note. Pulling the exhaust confirmed what I had suspected. The cat material was being sucked in and blown out during acceleration and deceleration.

Adding Vibrant race mufflers in place of the cats definitely increased the sound of the exhaust note too.

Scary stuff right there.

 

[SheepDog]

Has anyone pulled their exhaust and done an inspection of the pipes to see if there’s an indication of the cats loosening up and starting to fail? When mine failed, I could hear the immediate change in the exhaust note. Pulling the exhaust confirmed what I had suspected. The cat material was being sucked in and blown out during acceleration and deceleration.

Adding Vibrant race mufflers in place of the cats definitely increased the sound of the exhaust note too.

Now I have to go home and pull my cats and inspect. Thanks alot

 

[NGOT8R]

Scary stuff right there.

Yessir! It sure is.

 

[rolfe.oliver]

I wouldn't do cats boosted., but I am also putting resonators back on my 350 and have the stock mufflers. I just wanted free flowing exhaust where it matters.

 

[ShadesOfBloo]

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