Catless/Catted DPs in Australia

[spookyfish]

Hi,

I need some advice from you kind folk.

I just ordered a set of AR catted DPs, although I would prefer the catless pipes from a performance perspective, I am not sure I really want the hassle of running an illegal mod, and I defiantly don't want any issuance issues.

Since pulling the pin I have started having second thoughts, wondering if I am doing the right thing? Thinking maybe just get the catless DPs and just maintain the cats in the mid pipes?

I guess I only have a small window of opportunity to change my mind, and looking for some other perspectives to help with the decision.

From researching this on the web my impression is that most people are biased towards catless pipes, including the shops installing these products.. how much thought is being given to other factors other than HP? legal/illegal, insurance, environment, resale? etc..

Thanks!

[jorge135]

Upon your research did you find any catted and catless dyno comparisons?
I'm still interested in getting myself AR catless dp's. Did not consider catted versions only because my overall goal is maximum gain. I'll deal with any consequences down the line. From my 2 years driving experience with my 135i I've found it does not attract much cop attention. So i figure as long as im doing being a hoon or driving like a d1ck i'll be pretty safe

[kaitan]

Originally Posted by jorge135

Upon your research did you find any catted and catless dyno comparisons?
I'm still interested in getting myself AR catless dp's. Did not consider catted versions only because my overall goal is maximum gain. I'll deal with any consequences down the line. From my 2 years driving experience with my 135i I've found it does not attract much cop attention. So i figure as long as im doing being a hoon or driving like a d1ck i'll be pretty safe

In general cops do not pull over any german cars unless they are driving reckless or hoon. Euro cars do not attract cops as much as JDM. Even with loud exhaust such as froop! I doubt he got pull over by any cop for just a random pull over/ inspection.

[spookyfish]

Originally Posted by jorge135

Upon your research did you find any catted and catless dyno comparisons?
I'm still interested in getting myself AR catless dp's. Did not consider catted versions only because my overall goal is maximum gain. I'll deal with any consequences down the line. From my 2 years driving experience with my 135i I've found it does not attract much cop attention. So i figure as long as im doing being a hoon or driving like a d1ck i'll be pretty safe

Unfortunately no, but I expect you would see a 10hp hit and sound would be similar to OE over the catless pipes.

If I end up getting the catted DPs, ill get a stock dyno done and one with the DPs if people are interested?

[spookyfish]

So here is a question, say I go with the catless and my cobb tune masks the CEL, what happens if I want to uninstall my tune to take into bmw service? I would expect that I would start getting CEL errors.

Also, when selling the car you have a responsibility for the car to be roadworthy, if you don't want to be liable for events down the track, it would probably be best to re-fit OE pipes before selling... i guess its not the end of the world, but its still a pain.

[jorge135]

From what I've read on the forums you won't get CEL with Cobb maps.
Just keep your oem dp's if you ever wanna revert back to stock.
You'll prob be better off selling the after market dp's separately

[MO3]

You won't get a CEL even after you uninstall Cobb.

[135]

If you have any concerns then perhaps catted DPs are for you. Catted DPs might also get rid of a little bit of raspiness, although, it may not be discernible. Catted DPs may also limit the amount of boost you can run (probably good for ~14psi).

Catless DPs plus standard secondary cats will result in some smelly fumes, although, I'm not sure how much different it would be to OE. Catless DPs do yield more power (I've read any where from 10-30 rwhp - maybe more with a proper tune). If you decide to change to catless DPs, then you could upgrade the mid-pipe secondary cat section to use aftermarket cats, which are more high-flowing than standard (i.e. less restrictive on power) - I'm not sure if they would provide a higher level of pollution control considering the OE are smaller secondary cats that probably don't do much anyway and I'm not sure how this combination would differ/compare to catted DPs - I'm just really trying to provide you with options for consideration. A benefit of this option is that you could make the aftermarket section interchangeable for different situations, i.e. street or track, to provide additional power when needed - a LOT easier/cheaper than constantly changing DPs (I don't know why anyone would do that!). From what I've read, the OE cats are 600-cell and 400-cell for the primary and secondary, respectively (the secondary might also be up to 600-cell).

Those that install catless DPs are probably mainly concerned about extracting every last bit of power, with most retaining the OE DPs and exhaust system for any future need or prospective buyer.

Overall, there's a combination of contributing factors (including the brand/type of DP you choose and your engine) and your results can really only be determined through (expensive) testing.

[spookyfish]

Originally Posted by 135

If you have any concerns then perhaps catted DPs are for you. Catted DPs might also get rid of a little bit of raspiness, although, it may not be discernible. Catted DPs may also limit the amount of boost you can run (probably good for ~14psi).

Catless DPs plus standard secondary cats will result in some smelly fumes, although, I'm not sure how much different it would be to OE. Catless DPs do yield more power (I've read any where from 10-30 rwhp - maybe more with a proper tune). If you decide to change to catless DPs, then you could upgrade the mid-pipe secondary cat section to use aftermarket cats, which are more high-flowing than standard (i.e. less restrictive on power) - I'm not sure if they would provide a higher level of pollution control considering the OE are smaller secondary cats that probably don't do much anyway and I'm not sure how this combination would differ/compare to catted DPs - I'm just really trying to provide you with options for consideration. A benefit of this option is that you could make the aftermarket section interchangeable for different situations, i.e. street or track, to provide additional power when needed - a LOT easier/cheaper than constantly changing DPs (I don't know why anyone would do that!). From what I've read, the OE cats are 600-cell and 400-cell for the primary and secondary, respectively (the secondary might also be up to 600-cell).

Those that install catless DPs are probably mainly concerned about extracting every last bit of power, with most retaining the OE DPs and exhaust system for any future need or prospective buyer.

Overall, there's a combination of contributing factors (including the brand/type of DP you choose and your engine) and your results can really only be determined through (expensive) testing.

Thanks for the info, that is mostly inline with what I have been able to find out during my research.

[spookyfish]

Ok so from what i can tell AR are using the 3" street racer cats shown here. These cats seem to be rated at 200 CPI.

The two options on the table are:

1. Upgrade to catless DPs + maintain/upgrade secondary cats.

2. Upgrade to catted DP + delete secondary cats.


At this stage I am leaning towards option 2, AR catted DPs and then maybe look at a custom cat back..

Hoping this way I loose 10hp on the DP and gain 5hp on the catback with a net of -5hp, while eliminating CEL, etc. This is probably a good daily driver setup and good for resale, and minimal impact in performance.

[Nugget]

You will probably still get a CEL with aftermarket catted downpipes unless you are using a tune.
Just get the catless ones.
Another interesting, if expensive, option is AR's resonated downpipes.

[sparoz]

Originally Posted by spookyfish

Ok so from what i can tell AR are using the 3" street racer cats shown here. These cats seem to be rated at 200 CPI.

The two options on the table are:

1. Upgrade to catless DPs + maintain/upgrade secondary cats.

2. Upgrade to catted DP + delete secondary cats.


At this stage I am leaning towards option 2, AR catted DPs and then maybe look at a custom cat back..

Hoping this way I loose 10hp on the DP and gain 5hp on the catback with a net of -5hp, while eliminating CEL, etc. This is probably a good daily driver setup and good for resale, and minimal impact in performance.

Catless DP cooks secondary cats - ie that should be first to go.

Otherwise, I am sure a few of us have 1M dps which is stock high flow. I believe Ian's tune is at 22psi?

[135]

Originally Posted by spookyfish

Ok so from what i can tell AR are using the 3" street racer cats shown here. These cats seem to be rated at 200 CPI.

The two options on the table are:

1. Upgrade to catless DPs + maintain/upgrade secondary cats.

2. Upgrade to catted DP + delete secondary cats.


At this stage I am leaning towards option 2, AR catted DPs and then maybe look at a custom cat back..

Hoping this way I loose 10hp on the DP and gain 5hp on the catback with a net of -5hp, while eliminating CEL, etc. This is probably a good daily driver setup and good for resale, and minimal impact in performance.

If you're happy, or more comfortable, with option 2 then go with that but I have a feeling that you will be in deficit by more that 5hp. If you replace the secondary cats with a custom cat back, then I've always like the sound of the Berk Technology Full Street exhaust system. Here are a couple YouTube examples (I keep listening to the first one!):

Catless DPs with Berk full street exhaust

Catted DPs with Berk full street exhaust

[spookyfish]

Originally Posted by 135

If you're happy, or more comfortable, with option 2 then go with that but I have a feeling that you will be in deficit by more that 5hp. If you replace the secondary cats with a custom cat back, then I've always like the sound of the Berk Technology Full Street exhaust system. Here are a couple YouTube examples (I keep listening to the first one!):

Catless DPs with Berk full street exhaust
http://www.youtube.com/watch?v=KslxhaowSQY

Catted DPs with Berk full street exhaust
http://www.youtube.com/watch?v=QmQJj-ZZCJw

Nice, I think I've listen to these a few times checking out clips myself.. I always find myself going back to this one:

AR Catted + Berk Resonated Mids + Eisenmann Quad Race Axle back