Cats and exhaust on tuned A6

[Quickshifter07]

Hey guys ,
I’m looking into getting a c7 A6 3.0 it’ll be my first car LOL , I know a good amount about cars but still haven’t had much experience since I’m still in high school. When I get it I was planning in getting it tuned probably stage 2 single pulley to start get an intake and a HX and tcu tune (melen) . Now I’ve heard of when you get the car tuned your cats will eventually fail or melt , can someone explain why this is , how do you know when your cats have failed and what are the options after that happens. I just wanna get a heads up before it happens so I know what to do , also is this an expensive failure because from I’ve heard it’s practically bound to happen , any other problems that comes with tuning these cars ?

[07S6]

I don't think its much of a concern on single pulley. Chances increase when you go dual pulley. I've been running a stage 2 single pulley tune with stock cooling for nearly 3 years with no signs of any cat failure, or any other issue for that matter. Just tune and enjoy!

[ANMS4]

I still think the cats are hit or miss, Stock cats have melted, I change out my cats for TP's with GSI cats after only a few months of STG2 DP with maybe like 5-6 WOT pulls and my cats were melting. I had about 90k on the stock cats( 3k on STG2 DP). Not saying 100% you will need to replace them just budget for them to melt.

Options are TP's or TP's with HFC's, You'll probably need 02 spacers of both options, I have yet to been able to get a sticker on my car due the cat readiness not being set :/

[ticklechicken]

I still think the cats are hit or miss, Stock cats have melted, I change out my cats for TP's with GSI cats after only a few months of STG2 DP with maybe like 5-6 WOT pulls and my cats were melting. I had about 90k on the stock cats( 3k on STG2 DP). Not saying 100% you will need to replace them just budget for them to melt.

Options are TP's or TP's with HFC's, You'll probably need 02 spacers of both options, I have yet to been able to get a sticker on my car due the cat readiness not being set :/
What are TP and GSI?

[Quickshifter07]

I still think the cats are hit or miss, Stock cats have melted, I change out my cats for TP's with GSI cats after only a few months of STG2 DP with maybe like 5-6 WOT pulls and my cats were melting. I had about 90k on the stock cats( 3k on STG2 DP). Not saying 100% you will need to replace them just budget for them to melt.

Options are TP's or TP's with HFC's, You'll probably need 02 spacers of both options, I have yet to been able to get a sticker on my car due the cat readiness not being set :/

Being able to pass emissions is a big thing for me , I was looking around and TP and HFC’s might be the best option . I’m assume adding HFC’s would negate the smell just run TP would have ? Also do you know what a setup like that would cost ?

[Quickshifter07]

What are TP and GSI?

TP = Test pipes and I’m assuming by GSI he mean GESI high flow cats which is a brand I think

[f4m0u5]

Being able to pass emissions is a big thing for me , I was looking around and TP and HFC’s might be the best option . I’m assume adding HFC’s would negate the smell just run TP would have ? Also do you know what a setup like that would cost ?

redstar sells hfc direct fit, thats what anm is runni g but they cost about 1400$

test pipes are around $550 . then to remove the baby resonators and add in some hfc will be about $450 (250 in magnaflow cats and 200 install inllace of resonators)

im having custom downpipes made with 2 magnaflow hfcs and the magnaflow resonated x pipe, and new flex pipes welded in and thats about 450 in labor / ss pipe and flex pipes. magnaflow x pipe 11385 was 120$ and the magnaflow cats 59955 were 120 ea.... plus test pipes. all in about $1300 for test pipes, high flow cats and custom downpipes. i might even save $550 and just gut my stock cats

keeping it 2.25 since its still plenty of flow and dont want drone that comes with larger pipeing

[wootwoot]

redstar sells hfc direct fit, thats what anm is runni g but they cost about 1400$

test pipes are around $550 . then to remove the baby resonators and add in some hfc will be about $450 (250 in magnaflow cats and 200 install inllace of resonators)

im having custom downpipes made with 2 magnaflow hfcs and the magnaflow resonated x pipe, and new flex pipes welded in and thats about 450 in labor / ss pipe and flex pipes. magnaflow x pipe 11385 was 120$ and the magnaflow cats 59955 were 120 ea.... plus test pipes. all in about $1300 for test pipes, high flow cats and custom downpipes. i might even save $550 and just gut my stock cats

keeping it 2.25 since its still plenty of flow and dont want drone that comes with larger pipeing

Keep us posted and share sound clips if you can. I'm hesitant to go beyond stage 1 since there isn't an easy fix for the cat issue without spending big $$$ or adding drone. Your plan sounds like a good one, I'd be happy to see and hear more once it's complete.

[Quickshifter07]

Keep us posted and share sound clips if you can. I'm hesitant to go beyond stage 1 since there isn't an easy fix for the cat issue without spending big $$$ or adding drone. Your plan sounds like a good one, I'd be happy to see and hear more once it's complete.

From what I’ve heard your mostly ok at single pulley stage two it’s when you go to dual pulley when it’s almost guaranteed. I’d say if you have proper cooling you could go single pulley with no problems which will probably be what I end up doing .

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Also quick question say my cats do melt... what happens then how do I know they melted or failed , and what are the possible dangers of them melting while driving

[f4m0u5]

Keep us posted and share sound clips if you can. I'm hesitant to go beyond stage 1 since there isn't an easy fix for the cat issue without spending big $$$ or adding drone. Your plan sounds like a good one, I'd be happy to see and hear more once it's complete.

will definitely let you know, might be awhile though since my wifes only working 30% of her normal precovid... i will be having the cats and flex pipes installed, then later remove or gut and replace stock cat. My flex pipes are on way out and one leaking... so im getting the cats installed soon and wil be runing stock plus magnaflow cats for a little

[prestige.phantom]

Being able to pass emissions is a big thing for me , I was looking around and TP and HFC’s might be the best option . I’m assume adding HFC’s would negate the smell just run TP would have ? Also do you know what a setup like that would cost ?

HFC will pass with an O2 sensor spacer in most cars. Idk about the C7 A6 personally, but thats the case with most cars, from my understanding. HFC's do not negate the smell, typically but it all depends on the size of the cats. For example, my brother has a STG2 GTI with CTS HFC and it smells like fuel all the time.

[Patrick Matte]

From what I’ve heard your mostly ok at single pulley stage two it’s when you go to dual pulley when it’s almost guaranteed. I’d say if you have proper cooling you could go single pulley with no problems which will probably be what I end up doing .

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Also quick question say my cats do melt... what happens then how do I know they melted or failed , and what are the possible dangers of them melting while driving

You will feel a lost of power, engine cylinders will be high in the second cylinders bank ( cyl 4-5-6 ) this can occur on damage on your engine.

I installed test pipe after 2 weeks of being dual.

Sound was horrible ! Crispy and metal clicking was atroce !

I added magnaflow 11385 with S5 catback ! No more rasp , sound is deep, no drone ! Perfect !


Then one of my flexible broke ! I changed the two at the same time ! Now sound is better and no vibration, I had a leak between the test pipe and downpipe. I took 2.5 inch flexible to fit with the test pipe.

Now I love my exhaust !


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[wootwoot]

You will feel a lost of power, engine cylinders will be high in the second cylinders bank ( cyl 4-5-6 ) this can occur on damage on your engine.

I installed test pipe after 2 weeks of being dual.

Sound was horrible ! Crispy and metal clicking was atroce !

I added magnaflow 11385 with S5 catback ! No more rasp , sound is deep, no drone ! Perfect !


Then one of my flexible broke ! I changed the two at the same time ! Now sound is better and no vibration, I had a leak between the test pipe and downpipe. I took 2.5 inch flexible to fit with the test pipe.

Now I love my exhaust !


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Can you post some clips?

[p3u]

You do not need to remove your cats at stage 2 dual pulley. I have had stock cats for ~60k of ~110k miles on my car and have had cats off twice with no degradation of material.

I personally know dozens of people with dual pulley setups and have only seen it happen once, and it only failed in terms of being efficient enough for emissions. Cat failure is incredibly rare and is almost always a result of fueling problems.

[Patrick Matte]

You do not need to remove your cats at stage 2 dual pulley. I have had stock cats for ~60k of ~110k miles on my car and have had cats off twice with no degradation of material.

I personally know dozens of people with dual pulley setups and have only seen it happen once, and it only failed in terms of being efficient enough for emissions. Cat failure is incredibly rare and is almost always a result of fueling problems.

How is your driving habit ? dd ?

I know you know what you’re talking about John.


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[Patrick Matte]

Can you post some clips?

Yes i can do that ! I’ll do it tomorrow.


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