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Hi guys,

I've just bought a 2007 RS4 and naturally the first thing I wanted to do is make it a bit louder..

So I took it to the exhaust Shop and told them to remove the middle resonators, keep the flaps open, delete primary cat and install the 90degree O2 spacer.

Theyve done everything right apart from they have removed the main big cat and left the pre cat in!!

It does sound great but does this mean I don't get the power gains I would have done? Also I imagine I'll be 100% be getting a CEL now??

Cheers

amdaman wrote:Hi guys,

I've just bought a 2007 RS4 and naturally the first thing I wanted to do is make it a bit louder..

So I took it to the exhaust Shop and told them to remove the middle resonators, keep the flaps open, delete primary cat and install the 90degree O2 spacer.

Theyve done everything right apart from they have removed the main big cat and left the pre cat in!!

It does sound great but does this mean I don't get the power gains I would have done? Also I imagine I'll be 100% be getting a CEL now??

Cheers

If you asked them to remove the primary cats as you typed above, instead of pre-cats which you intended, they seem to have done what you asked.

What did you actually want, all the cats removed or just the pre-cats?

That's a typo but thanks for the feedback..

I supplied a picture of the JHM arrangement that shows the main cats in and the new O2 location behind the main cats. I thought that would have been sufficient.

That's not really the debate anyway, I just want to know if I should get it corrected or leave it as is to save the hassle.

Edit: just wanted the pre cats removed as after searching that seems to be the most popular route to a minor power gain plus sound.

Cheers

The pre-cats are 200cell (the same spec as many aftermarket "sports cats"), whereas the main cats are 400cell.

They've still removed some restriction, but personally I'd want it re-done properly...have they binned the pre-cats?


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Just re-reading your post, I'm wondering if you're US based. I have no idea what the requirements are where you live - Do you need any cats?


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Hi,

I'm based in New Zealand so there are no emissions requirements here. I'm hoping they haven't binned the cats but I'll find out tomorrow.

I'm starting to think if I don't lose power I might keep the setup as the hassle sounds annoying but I'll see what the Shop comes back with tomorrow. I don't think the CEL will come on as the O2 sensors are still before and after the pre cats aren't they? They installed an O2 extender elbow as well anyway.

amdaman wrote:Hi,

I'm based in New Zealand so there are no emissions requirements here. I'm hoping they haven't binned the cats but I'll find out tomorrow.

I'm starting to think if I don't lose power I might keep the setup as the hassle sounds annoying but I'll see what the Shop comes back with tomorrow. I don't think the CEL will come on as the O2 sensors are still before and after the pre cats aren't they? They installed an O2 extender elbow as well anyway.

Oh in that case mite.. bin the lot! Straight pipes, rear silencer! And install the exhaust controller to silence that bad boi for those trips to the Dairy with you Nan Bro! Choice!


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Hey im in NZ too and have just been through the whole primary and secondary removal gig with tuning etc.

Pm me your number and I can call you to discuss.

pule333 wrote:

amdaman wrote:Hi,

I'm based in New Zealand so there are no emissions requirements here. I'm hoping they haven't binned the cats but I'll find out tomorrow.

I'm starting to think if I don't lose power I might keep the setup as the hassle sounds annoying but I'll see what the Shop comes back with tomorrow. I don't think the CEL will come on as the O2 sensors are still before and after the pre cats aren't they? They installed an O2 extender elbow as well anyway.

Oh in that case mite.. bin the lot! Straight pipes, rear silencer! And install the exhaust controller to silence that bad boi for those trips to the Dairy with you Nan Bro! Choice!


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You've been hanging round with Rob too long!

But yeah, you could just ditch the cats then!


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FaisalJ wrote:

pule333 wrote:

amdaman wrote:Hi,

I'm based in New Zealand so there are no emissions requirements here. I'm hoping they haven't binned the cats but I'll find out tomorrow.

I'm starting to think if I don't lose power I might keep the setup as the hassle sounds annoying but I'll see what the Shop comes back with tomorrow. I don't think the CEL will come on as the O2 sensors are still before and after the pre cats aren't they? They installed an O2 extender elbow as well anyway.

Oh in that case mite.. bin the lot! Straight pipes, rear silencer! And install the exhaust controller to silence that bad boi for those trips to the Dairy with you Nan Bro! Choice!


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You've been hanging round with Rob too long!

But yeah, you could just ditch the cats then!


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Lol you forgetting the wife is a kiwi as well


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As it stands you won't get a CEL light.

FaisalJ wrote: ↑

Tue Oct 24, 2017 7:45 am

The pre-cats are 200cell (the same spec as many aftermarket "sports cats"), whereas the main cats are 400cell.

They've still removed some restriction, but personally I'd want it re-done properly...have they binned the pre-cats?


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Isn't it the other way around? I thought the pre-cats were 400 cell, that's why they bin them?

Huwbert wrote: ↑

Tue Oct 24, 2017 5:23 pm

FaisalJ wrote: ↑

Tue Oct 24, 2017 7:45 am

The pre-cats are 200cell (the same spec as many aftermarket "sports cats"), whereas the main cats are 400cell.

They've still removed some restriction, but personally I'd want it re-done properly...have they binned the pre-cats?


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Isn't it the other way around? I thought the pre-cats were 400 cell, that's why they bin them?

This was my understanding, pre-cats were very restrictive 400 cell and main cats were the same as some sports cats at 200 cell, with miltek offering both a 200 and 100 cell option.

Grandadg90 wrote: ↑

Tue Oct 24, 2017 12:36 pm

As it stands you won't get a CEL light.

If you get red of the main cats without a remap I thought you stood a good chance of getting a CEL? I recall some people reporting no CEL with no cats though. And can the engine run properly with no main cats without a remap as this will surely be outside of the normal adjustable parameters?

Sorry - I have no idea what I was thinking.

Precats are more restrictive 400cell.

Half asleep on a train into work after a late night in the office = nonsense. Apologies


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