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Discussion Starter · #1 ·
I was thinking about the autotech downpipe to the stock cat. Anyone know what diameter the stock cat is? I know autotech dp is 2.5 and stock exhaust is 2.25? is the stock cat 2.25 as well? any helpful info would be appreciated. Thanks in advance http://****************.com/smile/emthup.gif http://****************.com/smile/emthup.gif
 

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Re: Downpipe Question? (JusDubn)

Quote, originally posted by JusDubn »
Your cat is part of your stock DP. Most aftermarket DP's come with an attached cat.

The Autotech DP is just a short section with a flex joint. You have to cut your stock cat off and weld it onto the Autotech peice.
 

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Re: Downpipe Question? (greasyginzo)

Quote, originally posted by greasyginzo »

The Autotech DP is just a short section with a flex joint. You have to cut your stock cat off and weld it onto the Autotech peice.

Good to know but that sounds like a PITA! What do they charge for this Autotech DP?
 

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Discussion Starter · #6 ·
Re: Downpipe Question? (JusDubn)

I've read on the forums that a lot of the "high flow" cats are ceramic and not metal substrate like our OE cats. Thats why I was thinking about sticking with the stock one. And I think I read somewhere else that our stock cats flow pretty well. Anyone know if theres any truth to this. I was just goign to take the down pipe to a shop and have them install it and weld it onto the stock cat or however it works. Has anyone done this before?
 

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Re: Downpipe Question? (Black Magic Gli)

basically, you are getting a 2.5 inch pipe which opens the exhaust up, then going through your stock cat shrinks it right back down. its a little counterintuitive. think about spending the 200-300 dollars extra and get a milltek or tt dp. autotech guys are great guys tho.
 

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Discussion Starter · #8 ·
Re: Downpipe Question? (PeteRox)

Yeah that and the fact that the DP is only $200 is great. I bought a cam & upperstress bar for my old jetta from these guys so I had nothing but good experiences.
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Quote, originally posted by PeteRox »
basically, you are getting a 2.5 inch pipe which opens the exhaust up, then going through your stock cat shrinks it right back down. its a little counterintuitive. think about spending the 200-300 dollars extra and get a milltek or tt dp. autotech guys are great guys tho.
 

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Discussion Starter · #9 ·
Re: Downpipe Question? (Black Magic Gli)

Does anyone know what the size of the exhaust part of the turbo is? is it 2.5" or 3"? Reason I'm asking is I'm trying to figure out what's really restrictive. Is it just the factory downpipe, or the entire exhaust? From what I've seen and heard, it seems like it's just the downpipe. A downpipe by itself removes most of the restriction and adds more power. In other words you gain more power by changing the dp than dp & exhaust. Exhausts only add a few ponies. Can someone correct me if I'm wrong and point out the post that shows otherwise. Thanks
 

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Re: Downpipe Question? (Black Magic Gli)

it's true that metal cats flow better...
milltek offers a 3"downpipe>>2.5" downpipe>>>metal cat
i would recommend you to get the Milltek downpipe instead of the autotech...but if you're short in cash...save nikka!
 

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Re: (Black Magic Gli)

its not just the downpipe that is restrictive it is the stock cat.
are there any specific questions beyond the ones we already answered that you have? Think of it like this...lets say your aftermarket downpipe is a large piece of PVC pipe, and you don't upgrade your cat, therefore you have this large piece of PVC connected to your stock cat (we'll use a pixie stick as an example) then you have an aftermarket 2.5 inch cat back (another piece of large PVC). Now, try imagine flowing air through all three parts together.

now. the water or air in our case, is breathing freely then chocked through the skinny stock (causing backflow or less power). then freely out into the cat back.
conclusion: go with a high flow cat like i said in my other post. keep the air moving free, or otherwise you are just shooting yourself in your foot.




Modified by PeteRox at 2:28 PM 8-24-2006
 

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I just installed the autotech downpipe and exhaust. quality and fit was perfect. the install was not to bad either. The downpipe needs to be welded to the Cat. I cut the cat just about where it met the downpipe at 2.5 inches. so there is no loss in diamater. Except for at the end of the cat where it connects to the exhaust, I believe at 2.25in then back to 2.5in. Not so happy about that but the guys who helped me with the install said that was more than anough for the stock turbo. All and all I am very happy with the set up. great quality, definitely pulls alot harder. and it sounds perfect to me, not to loud. this is a great product for about $600 and you can't go wrong with the stock cat, no CEL


Modified by NjGTINj at 8:17 AM 8-25-2006
 
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