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      08-05-2011, 06:49 PM   #1
mrrosie
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OZ Catless downpipe questions

Hi all, just a newbie to the forums but a \"veteran\" 2008 135I owner with admittedly very limited knowledge in engines etc.

I have been trying to search on my app (as that is the main way I view the forum - I don\'t access a pc much) and haven\'t had any luck with finding answers the following q\'s. So apologies if these have already been asked...

1. Are catless dps legal in Australia?

2. Are the dps worth getting and why? Sound? Power? Better for the engine?

3. Do you know of any places in Sydney where they can be purchased and professionally installed?

Thanks!!
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      08-05-2011, 07:23 PM   #2
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1. Are catless dps legal in Australia?
- Nothing catless is legal in Aust. But in my opinion our cars have 3 cats, i'm sure removing the one of the DP wont hurt as long as the cops see that you have one on each of the 2 pipes.

2. Are the dps worth getting and why? Sound? Power? Better for the engine?
-Sound, power and freedom for your turbo's. Definitely a mod worth getting!

3. Do you know of any places in Sydney where they can be purchased and professionally installed?
- Purchased is a NO.. you will have to get them from the USA. Installed YES any exhaust centre should be able to do it, although one that has previous experience is strongly recommended!!

Hope that helps
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      08-05-2011, 08:33 PM   #3
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Ahhhh. The N54 has 4 cats mate. Two off the turbos and two on the midpipes. I have removed the two midpipe cats and the resonator.
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      08-05-2011, 10:00 PM   #4
mrrosie
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Thanks for the reply!!

Looks like I'll be doing the dps as my next mod.
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      08-05-2011, 11:43 PM   #5
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Just noticed that AR have the DPs in both catless and with cats now for a little bit extra....

In your opinion (once again with me not being too tech minded) shall I fork out for the with cat option?

Is there much difference between them?
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      08-05-2011, 11:58 PM   #6
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Quote:
Originally Posted by mrrosie View Post
Just noticed that AR have the DPs in both catless and with cats now for a little bit extra....

In your opinion (once again with me not being too tech minded) shall I fork out for the with cat option?

Is there much difference between them?
If you going to all the trouble to purchase and install DP's, you really can't go pass catless... Its the only way to go with Dp's to get maximum performance gains.
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      08-05-2011, 11:59 PM   #7
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Go catless if you have a tune. Catless=More power. You will need a tune to delete the catalytic converter codes. I think the catted are a waste of money.
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      08-06-2011, 12:40 AM   #8
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If you are going to go catted ar dps then save the $1200 and leave what you got because your gains will be very small and you wont even notice them when driving.
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      08-06-2011, 01:00 AM   #9
mrrosie
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Thanks again guys, your feedback helped a lot!
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      08-06-2011, 03:42 AM   #10
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Quote:
Originally Posted by Zuzu View Post
If you going to all the trouble to purchase and install DP's, you really can't go pass catless... Its the only way to go with Dp's to get maximum performance gains.
That's it.
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      08-07-2011, 08:58 PM   #11
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Oh yeah my fumble Zuzu thanks for pointing that out

I will be hopefully installing DP's soon.. mine are catless.. but the midpipes will have cats on. They will 100cpi so they almost AREN'T cats if you know what im saying
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      09-30-2018, 09:53 PM   #12
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Has anyone been caught by cops/epa with Catless downpipes (N54)? If I leave the midpipe it's still technically catted right?
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      11-22-2018, 02:13 AM   #13
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Quote:
Originally Posted by NinjaDog View Post
Has anyone been caught by cops/epa with Catless downpipes (N54)? If I leave the midpipe it's still technically catted right?
if you have to do an EPA test, you'll fail.

if you get a thorough roadside inspection, you'll pass because only enthusiasts and mechanics know there should be primary and secondary cats on a N54. ... anyone else is going to see the secondary cats and say "yup, that's catted.".

also, because of the secondary cats, a car with carless downpipes doesn't smell like a car with no cats.
(a straight piped exhaust has a faint fireworks smell)
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      11-22-2018, 11:39 PM   #14
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I was told by a workshop that there is a difference but not a huge one. think 5kw or something, give or take, pending conditions etc.
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      11-23-2018, 01:17 AM   #15
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Quote:
Originally Posted by dainese View Post
I was told by a workshop that there is a difference but not a huge one. think 5kw or something, give or take, pending conditions etc.
If you run a stock tune, that might be correct; but if you're looking to up your PSI (ie. run MHD Stage 2), the exhaust and intake restrictions are important.

The stock intercooler is restrictive, but nothing like the restriction caused by your primary cats.

If you want to go cheap, do it DIY. Take your stock downpipes off and bash the the primary cats out with a crowbar, then re-install them. It'll give you 90% of the benefit of VRSF downpipes for the cost of a couple of gaskets and a few hours of your time (maybe 10).

But the general consensus among the n54 tuning community is that your downpipes should be the first mod you make. Intercooler is your second.
(after the parts that are prone to fail - eg. coils and your chargepipe)
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      11-25-2018, 06:06 PM   #16
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Quote:
Originally Posted by xQx View Post
If you run a stock tune, that might be correct; but if you're looking to up your PSI (ie. run MHD Stage 2), the exhaust and intake restrictions are important.

The stock intercooler is restrictive, but nothing like the restriction caused by your primary cats.

If you want to go cheap, do it DIY. Take your stock downpipes off and bash the the primary cats out with a crowbar, then re-install them. It'll give you 90% of the benefit of VRSF downpipes for the cost of a couple of gaskets and a few hours of your time (maybe 10).

But the general consensus among the n54 tuning community is that your downpipes should be the first mod you make. Intercooler is your second.
(after the parts that are prone to fail - eg. coils and your chargepipe)
Yeah, I take your point. Makes sense too.

I am a walking contradiction as I care about emissions but also love cars too!

See how I go
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