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high-flow catalytic converter

well, my car's exhaust is starting to stink like rotten eggs (sulphur) so i figure my catalytic converter is going

i figure if i gotta replace something, might as well see if i can upgrade it, so i looked into high-flow catalytic converters

http://www.speedyperformanceparts.com/pacesetter-exhaust_po_944_high-flow-catalytic-converter_z.html

does anyone know if a high-flow cat (such as the one listed in the above link) will improve or hurt the performance of my '87 NA. i don't mind trading a little torque for some more high-end hp. (but only a little and must be an equal or better trade-off)

seems like the cat ($130) listed in that site is also a much better value than a stock cat ($500)

your advice is appreciated
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Old 02-04-2004, 08:25 PM
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I'd be careful buying a cat. They list them as being for the 944, but really they are just one size fits all, weld it in applications. Look around for a better 'brand' name source, or ask a good local muffler shop. I failed my first smog, so I bought a used cat from someone parting out a low mileage 944, tuned the car, and swapped out the O2 sensor. viola
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Old 02-04-2004, 10:07 PM
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dj. Can you by pass it or do you have inspections? Sman
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Old 02-05-2004, 03:04 AM
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Quote:
Originally posted by 924Sman
dj. Can you by pass it or do you have inspections? Sman
can't bypass it. must pass emissions
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Old 02-05-2004, 05:36 AM
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Quote:
Originally posted by lousailor
I'd be careful buying a cat. They list them as being for the 944, but really they are just one size fits all, weld it in applications. Look around for a better 'brand' name source, or ask a good local muffler shop. I failed my first smog, so I bought a used cat from someone parting out a low mileage 944, tuned the car, and swapped out the O2 sensor. viola
so what is a better brand name source?
any sites?
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Old 02-05-2004, 05:46 AM
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Quote:
Originally posted by dj_yen
can't bypass it. must pass emissions
May I suggest moving to Iowa....nothing to pass here but gas! Modified exhaust capital of the world! Heck I think go karts here have headers!

But you may try www.*************** they are really inexpensive on most all OEM parts. Check here or at Paragon also.

Happy Shopping! Sman
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Old 02-05-2004, 06:16 AM
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I will say that you really can't beat the stock exhaust on the car. Porsche did a very good job of tuning the exhaust and to tinker or change a component will effect performance. Mainly back pressure is changed and that can rob power on either end. So to install an aftermarket cat I would be very reluctant without some good testimonials to buy because it is a "good price"! They are cheaper for a reason. It may pass the emissions but not the guy next to you! Sman
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Old 02-05-2004, 06:26 AM
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Quote:
Originally posted by 924Sman
I will say that you really can't beat the stock exhaust on the car. Porsche did a very good job of tuning the exhaust and to tinker or change a component will effect performance. Mainly back pressure is changed and that can rob power on either end. So to install an aftermarket cat I would be very reluctant without some good testimonials to buy because it is a "good price"! They are cheaper for a reason. It may pass the emissions but not the guy next to you! Sman
when u say rob power on either end.......roughly how much....will it be that noticeable? cause the difference in price is pretty big
besides stock ......do u know of any other aftermarket brands that are worthy?
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Old 02-05-2004, 06:44 AM
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I wish I could be of more help but being cats for me is a another issue!hehe....so I have no need for looking in the market place.

Power will vary depending on the set up. Most often the low end is compromised. The hi end will differ with tube diameter and muffler or headers only rest stock or stock no cat etc. So it really is an area that one needs to see what others have installed and the pro's and con's.

If I were you I would replace with OEM and change only the muffler. This will give you a bit more flow with close to the needed back pressure.

If headers are installed I would also open the rest up and go catless. This way I can get the most out the headers as possible. I kringe when power is jepordized for cost. But I understand it.

Again power will vary but to be safe I would say 5 to 15 hp or more in more radical set ups. Sman
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Old 02-05-2004, 07:14 AM
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thanks for all the info.
sounds like i shouldn't get anything aftermarket unless it's been proven.
i've considered getting a freer-flowing cat back but i am aware to be careful not to upset the very balanced intake/exhaust system of a NA 944. the only reason why i am considering getting a high-flow cat is because my current one is in need of replacement.
the price of the OEM cat is damn expensive though. i'll check into used ones.
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Old 02-05-2004, 10:23 AM
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You can have mine! Find a set of used headers and test pipe and it's yours! Sman
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Old 02-05-2004, 11:45 AM
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Quote:
Originally posted by 924Sman
You can have mine! Find a set of used headers and test pipe and it's yours! Sman
Sman: Can't I just swap cat's? We have the same engine don't we?
What's your price? You can PM me if you prefer.
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Old 02-05-2004, 12:29 PM
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I agree with S-man. Not knowing the specs on the OEM cat, I swapped to a newer stock cat, and strapped a Flowmaster muffler on the back. Not sure if it actually helps or hinders performance (it should have freed up the backpressure), but it sure sounds like it, and it's tons of fun listening to car alarms go off when I burble by.
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Old 02-05-2004, 12:36 PM
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Why would I want a dead cat?! Sman
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Old 02-05-2004, 01:14 PM
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Quote:
Originally posted by 924Sman
Why would I want a dead cat?! Sman
he meant why can't he just take off his old cats and put on urs which are good? why the need for used headers and test pipe if all he needs are the cats
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Old 02-05-2004, 05:35 PM
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Quote:
Originally posted by NYC_SpeedRacer
he meant why can't he just take off his old cats and put on urs which are good? why the need for used headers and test pipe if all he needs are the cats
NO I want him to find me headers and test pipe for my cat! It was a smart a$$ remark.

And why would I want to install a dead cat when mine is good!

Simply put he can have my good cat for a set of headers and pipe. If he has headers and test pipe he can find. Sman
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Old 02-06-2004, 12:54 AM
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