# Catless downpipe pass emissions testing?



## earichmond (Sep 20, 2018)

Someone from BNR on the phone told me before that one catalytic converter passes PA emissions. Can anyone confirm this? Can’t find a clear answer online and worried for when the time comes around


----------



## JLL (Sep 12, 2017)

If you have to second guess yourself you probably shouldn't do it.


----------



## pandrad61 (Jul 8, 2015)

I very much doubt a cat less car will pass emissions.


----------



## Thebigzeus (Dec 2, 2018)

pandrad61 said:


> I very much doubt a cat less car will pass emissions.


Cruze has two cats though.


----------



## pandrad61 (Jul 8, 2015)

Thebigzeus said:


> Cruze has two cats though.


Two for a reason. GM wouldn’t put two just for the fun of it. Only way I can see it passing with 1 is if the tune had a emissions mode to run it in a way it can pass, but if ran for long then it could cause damage.


----------



## Snipesy (Dec 7, 2015)

Depends how smart they are.

Since there is literally 0 advantage to removing it I dont see the point. Other than murdering people I guess.


----------



## Thebigzeus (Dec 2, 2018)

pandrad61 said:


> Two for a reason. GM wouldn’t put two just for the fun of it. Only way I can see it passing with 1 is if the tune had a emissions mode to run it in a way it can pass, but if ran for long then it could cause damage.


Sure, I wasnt arguing the point of two cats. Just stating a fact.


----------



## Thebigzeus (Dec 2, 2018)

Snipesy said:


> Since there is literally 0 advantage to removing it I dont see the point. Other than murdering people I guess.


You don't think the turbo spools faster?


----------



## Snipesy (Dec 7, 2015)

Thebigzeus said:


> You don't think the turbo spools faster?


I think a sticker gives more ponies.


----------



## Thebigzeus (Dec 2, 2018)

Snipesy said:


> I think a sticker gives more ponies.


lol nice troll


----------



## JLL (Sep 12, 2017)

Snipesy said:


> I think a sticker gives more ponies.


Did somebody say *STICKERS*!!!??? 🤯


----------



## pandrad61 (Jul 8, 2015)

Thebigzeus said:


> Sure, I wasnt arguing the point of two cats. Just stating a fact.


Yah GM won’t waste the money so more then likely for someone who does the rest properly and cares then probably SOL. if you get minimum wage joe who couldn’t care less then you got a shot.


----------



## pandrad61 (Jul 8, 2015)

Snipesy said:


> Depends how smart they are.
> 
> Since there is literally 0 advantage to removing it I dont see the point. Other than murdering people I guess.


I’d disagree there. Even though today’s modern cats are way way better then in the past, you should still see HP and response gains.


----------



## JLL (Sep 12, 2017)

pandrad61 said:


> I’d disagree there. Even though today’s modern cats are way way better then in the past, you should still see HP and response gains.


If you think about it the stock output of the engine is AMAZING compared to engines of the past. 138 HP out of just 83 cubic inches (or 1.4L for those in other countries).

Now that doesn't mean there's not more power to be had. But historically that's some pretty good power out of such a small engine.


----------



## Snipesy (Dec 7, 2015)

pandrad61 said:


> I’d disagree there. Even though today’s modern cats are way way better then in the past, you should still see HP and response gains.


The ‘back pressure’ from the catalyst is basically 0 compared to the turbo.

On a natural aspirated engine you can see gains. As they don’t have a turbo. So relatively speaking the cats are a big source of back pressure. But on the Cruze the cats are a relatively small source.

Hopefully that makes sense. Like say the turbo has 100 units of back pressure the cat would have say 0.1. Removing the cat makes it 99.9. The difference? Too small to measure.


----------



## Noiitekk (Feb 28, 2017)

I pass emissions in CT with one cat. I deleted the first one and I’m tuned so no emissions codes.


----------



## pandrad61 (Jul 8, 2015)

JLL said:


> If you think about it the stock output of the engine is AMAZING compared to engines of the past. 138 HP out of just 83 cubic inches (or 1.4L for those in other countries).
> 
> Now that doesn't mean there's not more power to be had. But historically that's some pretty good power out of such a small engine.


One stipulation it’s a turbo engine. The 1.4 NA version is like 98hp in the spark. that’s less then a 100hp per liter. Poor by today’s standards but what better then the past.


----------



## pandrad61 (Jul 8, 2015)

Snipesy said:


> The ‘back pressure’ from the catalyst is basically 0 compared to the turbo.
> 
> On a natural aspirated engine you can see gains. As they don’t have a turbo. So relatively speaking the cats are a big source of back pressure. But on the Cruze the cats are a relatively small source.
> 
> Hopefully that makes sense. Like say the turbo has 100 units of back pressure the cat would have say 0.1. Removing the cat makes it 99.9. The difference? Too small to measure.


Not sure I think it’s that free flowing. Maybe the gains are small since the displacement and boost is small. Either way today’s cats are way way better then they use to be.


----------



## snowwy66 (Nov 5, 2017)

JLL said:


> If you think about it the stock output of the engine is AMAZING compared to engines of the past. 138 HP out of just 83 cubic inches (or 1.4L for those in other countries).
> 
> Now that doesn't mean there's not more power to be had. But historically that's some pretty good power out of such a small engine.


153 for the 2's


----------



## Thebigzeus (Dec 2, 2018)

Snipesy said:


> The ‘back pressure’ from the catalyst is basically 0 compared to the turbo.
> 
> On a natural aspirated engine you can see gains. As they don’t have a turbo. So relatively speaking the cats are a big source of back pressure. But on the Cruze the cats are a relatively small source.
> 
> Hopefully that makes sense. Like say the turbo has 100 units of back pressure the cat would have say 0.1. Removing the cat makes it 99.9. The difference? Too small to measure.


It definitely spools faster with a catless downpipe, no doubt. Now is that more power, well no, but the power comes on faster.


----------



## pandrad61 (Jul 8, 2015)

Thebigzeus said:


> It definitely spools faster with a catless downpipe, no doubt. Now is that more power, well no, but the power comes on faster.


I’m happy with better throttle response


----------

