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YOUR RESEARCHCatalytic converter from 2003 996 vs 2006 997
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Use cats have no warranty
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Used cats have no warranty from the sellers even from the EPA requirements that theybe warranted for 10 years or 50 k miles.
Leading evidence: 'Use cats have no warranty' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Use 996 cats' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Suggestion
to clarify, you can use 996 cats on a 997 if you hack off about 2�.
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Suggestion
You can use 997 cats on a 996 with an adapter like seen below.
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Suggestion
Answers my question on using 997 units, haha - thanks.
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Suggestion · Original poster
Are these aftermarket ones better than used OEM ones with 40k-60k miles, if prices are about the same?
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Just bought my 03 996 and had a pleasant surprise a few days into ownership. My CEL came on due to P0420 and I've been told I need a new catalytic converter. Since prices of new cats are insanely high, I found a used pair from a 2006 997.1 C2 (3.6L). Will these fit my 2003 996 C2 3.6L?
As per the various parts catalogs, the cat part numbers for the 2006 vs 2003 are different but they visually look the same. Is there a difference, if any? Should I purchase the catalytic converters from the 2006 car and attempt to install them in my 2003?
Thanks in advance!
Had the exact same scenario a couple months ago (bought car, started getting P0420/P0430 codes, fainted at cost of new cats). I looked around to see if 997 cats would fit, but consensus was there was a difference in diameter on pipes themselves. Guessing it could be made to work with a little creative fabrication, but I wanted to stay on the bolt-on path. Hoping someone jumps in to correct me if I'm wrong.
Wound up finding a pair of 2003 take-offs that fit my 2002 perfectly. Go to eBay, and search for "996 down pipes". You'll turn up more options than if you search for catalytic converters.
Good luck.
BTW, that first CEL when driving your new-to-you-but-could-blow-up-anytime-because-IMxB-996 is a fun moment of panic, amiright? :-)
Gotta be careful with aftermarket cats in CA & NY. Based on the description, it doesn't sound like these would pass inspection in either state (OP is in California).
Thanks for the tip on what to search on eBay! I now see all the used cats for sale now that I search for down pipes instead of catalytic converter. I was wondering how it was possible that no one was selling them.
And you're totally right, I got pretty nervous when that CEL came on. I think the previous owner knew about the problem and decided to sell the car to me without telling me all the hidden problems. Hopefully I don't find anymore.
Thanks for that info! I did see these for sale. The CA certified version of these was $100 more so I figured I'd rather get a used OEM cat for about that much that will guarantee no CEL issues or potential to fail smog.
What do you guys think? Are these aftermarket ones better than used OEM ones with 40k-60k miles, if prices are about the same?
Used cats have no warranty from the sellers even from the EPA requirements that theybe warranted for 10 years or 50 k miles.
Cats are a wear item as the reactive metals internally get used up. Without testing its a crapshoot if a used 40-60 k mile cat will be worth the investment.
Your best bet is buy new OEM. Expensive but question proof. Aftermarket seems to work for many.
Since this thread comes up if you search on google, I figured I'd add that 996 and 997 cats are identical- the pipe diameter is the same, but the exit pipe on the 997 cats are slightly shorter. The aftermarket X-pipe's I've seen include short spacers to make them both 996 and 997 compatible.
I suppose, if you were in a bind, you could get these small spacers to install 997 cats on your 996, or break out the hacksaw to install 996 cats on your 997.
--Aaron
I have 2 sets of 997 cats available, and I have a spacer on my car, if I can figure out where to get the short spacers they include with aftermarket cats then that will broaden the market for you.
My old 996 C4S came with a huge binder of service work. The year prior to me purchasing it (2023), the previous owner had spent $13k (!!!) for a set of original cats. WOW!
--Aaron
I�d also be interested in those short spacers for when you learn more about them.
Do you how much length is missing from the 997 cats? My vague memory recalls it was around 3 inches.
Here are the �extensions� I have that came with my aftermarket �one size fits all� (996 or 997) x-pipe.
to clarify, you can use 996 cats on a 997 if you hack off about 2�. You can use 997 cats on a 996 with an adapter like seen below.
�Aaron
