High Flow catalytic converters????
Thread Starter
Junior Member
Joined: May 2007
Posts: 65
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From: SoCal
2003 SL500, Lamborghini Gallardo
High Flow catalytic converters????
One of my catalytic converters are rattling from the inside. I have an Fab-Design cat back system on it and would like to increase the sound depth with some high flow cats. I dont want to bypass them or anything like that but since I have to replace them anyway, I thought something like the Magnaflows might work good.
Anybody using high flow cats?
Am I risking 02 sensor fault codes with aftermarket cats?
I heard a rumor that Calif law has dealers warranty cats for 4yrs or 50k miles, is this true?
TIA fellas......
______________
Anybody using high flow cats?
Am I risking 02 sensor fault codes with aftermarket cats?
I heard a rumor that Calif law has dealers warranty cats for 4yrs or 50k miles, is this true?
TIA fellas......
______________
Newbie
Joined: Feb 2008
Posts: 8
Likes: 0
1973 280se
I don't know about warranties, etc, but I can tell you two things about the high-flow cat I put on my 4.0 liter Jeep (as part of a 2.25" Borla header/Flowmaster system): it radically reduced backpressure and it notably increased the exhaust noise. The increased exhaust noise is a bummer, frankly...
Oh, it's neat when you first hear it, and it impresses people to hear the throaty rumble, but it's louder on the highway, louder in the neighborhood during quiet times and really telegraphs what I'm doing with the throttle on the freeway ramp, etc... I wanted the truck to have more ooomph, but didn't need the extra hotrod sound. Think about that if you're going to uncork your Benz, too.
Oh, it's neat when you first hear it, and it impresses people to hear the throaty rumble, but it's louder on the highway, louder in the neighborhood during quiet times and really telegraphs what I'm doing with the throttle on the freeway ramp, etc... I wanted the truck to have more ooomph, but didn't need the extra hotrod sound. Think about that if you're going to uncork your Benz, too.
MBWorld Fanatic!
Joined: Sep 2005
Posts: 6,189
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From: Albuquerque
'10 CL550, '12 GL550
Don't get excited about "high flow." It's just hype to impress hot rodders.
It may be better than what comes on Jeeps, but it's not better than what comes on Mercedes.
All cats on all vehicles sold anywhere in the USA are warranted for 8 years/80K miles.
It may be better than what comes on Jeeps, but it's not better than what comes on Mercedes.
All cats on all vehicles sold anywhere in the USA are warranted for 8 years/80K miles.
Member
Joined: Aug 2007
Posts: 197
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From: Long Island, NY
'03 C320 Sedan, '04 SAAB 9-3 Cabrio
Super Member
Joined: Apr 2002
Posts: 592
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From: Sacramento
AMG C43, 1999
The 200 cell race cats I have seen have all been very expensive. Magnaflow or Catco makes some pretty nice Cats with a metal substrate and fairly nice tapered pipe sections leading to the cat honeycomb section.
Most stock cats, MB included dont have any taper going from the pipe to the cat and so the exhaust gas hits this increased area and slows down and becomes turbulent. With a nice 7-10 degree taper on both sides of the honeycomb cat section the exhaust flow will stay laminar and will more somoothly enter the cats and exit better, which will result in an increased flow. also the metal substrate cats have a thinner x-section and this also helps to reduce backpressure vs. a longer ceramic cat honeycomb section.
If someone has a source for resonalbe priced 200 cell cats, please share.
Jeff
Most stock cats, MB included dont have any taper going from the pipe to the cat and so the exhaust gas hits this increased area and slows down and becomes turbulent. With a nice 7-10 degree taper on both sides of the honeycomb cat section the exhaust flow will stay laminar and will more somoothly enter the cats and exit better, which will result in an increased flow. also the metal substrate cats have a thinner x-section and this also helps to reduce backpressure vs. a longer ceramic cat honeycomb section.
If someone has a source for resonalbe priced 200 cell cats, please share.
Jeff
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Senior Member
Joined: Oct 2008
Posts: 400
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From: SD
00 e55
Make sure your replacement cats are metal and not ceramic substrate as ceramic does not last as long, does not withstand higher temperatures as good especially on a big Mercedes motor. And unless they are 200 cell they are not really high flow cats.
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