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High flo cat to make car livable?

Old 12-06-18, 11:52 PM
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High flo cat to make car livable?

What are your thoughts on high flow catalytic converters and are there any "good" ones? I've had an open mid pipe there for 15 years or so and it sounds cool and probably adds some HP. The problem is that I stink like a gas station attendant after a long shift in the summer every time I drive the car anywhere. I wonder if a high flow would at least aid some in cleaning up the exhaust? I'd rather not put the huge and heavy stock piece back on and I've long since rid myself of the airpump....

Any other ideas are welcome too.
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Old 12-07-18, 05:36 AM
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I bought my car 16 years ago with a BONEZ hi-flow cat and it wasn't new then. 11 years ago I removed emissions and began pre-mixing WITH a working OMP. The cat is still going strong (I pull it off occasionally and inspect the matrix). All stainless, good welds, thick flanges and NO stink. Can't comment on the others...and there are others. But it's never given me a reason to complain.
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Old 12-07-18, 07:05 AM
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Yep. I've got an SMB high flow cat that I've had for 10-12 years, never run with an air pump, does the job great. Gets rid of the stink or at least gets it to manageable levels.

Bonez is the easy go-to here, they're top quality, flow great, are reasonably priced, and will hold up over time.

I've done back-to-back butt dyne tests with a mid pipe and my SMB cat, with twins making low-mid 300's. Very minor difference if any.

Go for it, you'll be happy you did.

Dale
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Old 12-07-18, 07:15 AM
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Another vote for Bonez. The whole piece is top quality and they do a neat trick with bowed flanges to get it to seal more reliably.

As far as stink goes... you should temper your expectations. You will still experience some stink if you don't have an air pump. I've got my idle AFR tuned and if I disconnect my air pump it stinks up the general area in no time.
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Old 12-07-18, 10:26 AM
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I have had three different aftermarket cats over the years. Two of which are mentioned above, which are both very good.
IMO, here are how I would rank them.
#3- SMB 100 cell Good- smell was OK, not gone but mostly mimimal at idle AFR of 13- turbo spool was better than Bonez possibly due to less backpressure- came as complete midpipe Bad- unfortunately, the metal internals partially melted after a few years
#2- Bonez Good- smell was OK, not gone but mostly mimimal at idle AFR of 13, similar to SMB- came as complete midpipe Bad- turbo spool was definitely delayed as compared to SMB or Vibrant- some people have described clogging in the past, I didn't experience this
#1- Vibrant 300 cell racing cat GESI-UHO- my current cat- no smell at idle as long as AFR of 13- minimal smell if below 13- best for turbo spool, I believe the least backpressure- CARB OBD2 rated (California rated for emissions) Bad- must be welded into current midipipe, more work

Mike
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Old 12-07-18, 07:43 PM
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Originally Posted by mikejokich View Post
I have had three different aftermarket cats over the years. Two of which are mentioned above, which are both very good.
IMO, here are how I would rank them.
#3- SMB 100 cell Good- smell was OK, not gone but mostly mimimal at idle AFR of 13- turbo spool was better than Bonez possibly due to less backpressure- came as complete midpipe Bad- unfortunately, the metal internals partially melted after a few years
#2- Bonez Good- smell was OK, not gone but mostly mimimal at idle AFR of 13, similar to SMB- came as complete midpipe Bad- turbo spool was definitely delayed as compared to SMB or Vibrant- some people have described clogging in the past, I didn't experience this
#1- Vibrant 300 cell racing cat GESI-UHO- my current cat- no smell at idle as long as AFR of 13- minimal smell if below 13- best for turbo spool, I believe the least backpressure- CARB OBD2 rated (California rated for emissions) Bad- must be welded into current midipipe, more work

Mike
Cool. I'm looking for a bolt on so I think I'll go with the BoneZ, plus as an old skater, the name is cool. If I can just temper it a small amount then that is realistically what I'm after.
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Old 12-07-18, 07:43 PM
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Originally Posted by DaleClark View Post
Yep. I've got an SMB high flow cat that I've had for 10-12 years, never run with an air pump, does the job great. Gets rid of the stink or at least gets it to manageable levels.

Bonez is the easy go-to here, they're top quality, flow great, are reasonably priced, and will hold up over time.

I've done back-to-back butt dyne tests with a mid pipe and my SMB cat, with twins making low-mid 300's. Very minor difference if any.

Go for it, you'll be happy you did.

Dale
Copy that. Just took the car to Rick's today and got the news... 2nd blown motor.... it may be a while.
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Old 12-07-18, 07:45 PM
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Where to buy this piece? RX7 Store??
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Old 12-08-18, 06:01 AM
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Originally Posted by Donovan View Post
. got the news... 2nd blown motor.... it may be a while.
Did they say what caused it?
Originally Posted by Donovan View Post
Where to buy this piece? RX7 Store??
http://rx7.com/store/rx7/fdexhaust.html
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Old 12-08-18, 07:07 AM
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I have a bonez with an air pump and there's no smell and the car drives well. But in my opinion, it's not as nice as newer converters.

I'm general, Im dissapointed that there's no other bolt on options, with a modern metallic core. Years ago there was random technology, and smb, etc. Outside of a few Japanese companies making some expensive ones, there are not many options.

A bolt in option with the vibrant cat mentioned above would sell well imo. I think most rx7 owners are outgrowing the open exhaust smell and would use a catted pipe if there was a good option that flowed well. My last car made 454 rwhp with a random cat, so one can have performance and no stink.
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Old 12-09-18, 01:29 PM
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I just put a cat in mine to pass inspection. It's nice being able to hear the stereo and not reeking. I might switch it out for big weekends but daily driving it is staying. Got mine from rx7store.
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Old 12-11-18, 08:27 AM
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Read a few threads about this lately, probably going to give the vibrant cat a try this spring when the cars out of storage from winter
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Old 12-11-18, 12:44 PM
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Had the car on the same dyno years ago, based on my poor recollection l believe there was a 10 rwhp difference between the Bonez and midpipe
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Old 12-11-18, 08:54 PM
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I've had the magnaflow unit that rx7store sells for a few years on my cars. I love them. All stainless, perfect fit, nice and fat magnaflow cores and the exhaust tones are beautiful and deep. They tuck up so nicely into the chassis you would think they were stock
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Old 12-11-18, 09:18 PM
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The Magnaflow unit from Rx7store is a resonates midpipe.
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Old 12-11-18, 10:18 PM
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It has all the honeycomb in it though. It's not straight through with the chamber around it. Am I not understanding correctly?
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Old 12-15-18, 04:18 PM
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Originally Posted by cr-rex View Post
It has all the honeycomb in it though. It's not straight through with the chamber around it. Am I not understanding correctly?
the magnaflow midpipe is a muffler. He is speaking of cats.
speaking of which cr-rex what muffler you have with that midpipe?
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Old 12-15-18, 04:51 PM
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I just purchased a hiflow cat from Rx7 store and can confirm it is Magnaflow brand.
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Old 12-15-18, 04:57 PM
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Hmmmm, well that's good to know. I didnt know they sold a cat.
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Old 12-15-18, 10:04 PM
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Originally Posted by Testrun View Post
the magnaflow midpipe is a muffler. He is speaking of cats.
speaking of which cr-rex what muffler you have with that midpipe?
that's a very confusing post but it's the magnaflow mid pipe/hi flow cat (whatever were calling it) with an re dolphin tail. It's a beautiful sound and means the world to me
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Old 12-15-18, 10:10 PM
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Originally Posted by cr-rex View Post
that's a very confusing post but it's the magnaflow mid pipe/hi flow cat (whatever were calling it) with an re dolphin tail. It's a beautiful sound and means the world to me
LOL!!!!
I apologize and am very happy you like it so much.
Sorry not trying to confuse. I have a magnaflow mid pipe from RX7store that is not a cat. I spoke to soon and assumed you meant the muffler/midpipe and not the cat.
I guess I have always called a cat a cat. Not a midpipe. A midpipe to me is what would replace a cat.

Enjoy that beautiful sound!!!!
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Old 12-16-18, 07:41 AM
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Originally Posted by cr-rex View Post
that's a very confusing post but it's the magnaflow mid pipe/hi flow cat (whatever were calling it) with an re dolphin tail. It's a beautiful sound and means the world to me
I thought I hit the submit button on my last reply.

LOL!!!! I apologize and am very happy that you are pleased with your mid pipe/highflow cat.
I jumped to conclusions. I have always called a mid pipe a mid pipe. A mid pipe replaces a cat. A cat is a cat. So the magnaflow mid pipe I have from RX7store is a pipe with a magnaflow muffler on it. I was unaware that they made a magnaflow midpipe cat. Apologies!!
. And again I am very happy to see you are please with your sounds!! I only asked since I am running an RB dual tip and getting ready to install my mid pipe. If it is too loud or smelly, then I will simply go back to my cat! I have a pettit highflow cat. I am not sure how long it will last. It has a chemical smell to it for sure once hot.
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Old 12-17-18, 03:22 PM
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Originally Posted by books View Post
Had the car on the same dyno years ago, based on my poor recollection l believe there was a 10 rwhp difference between the Bonez and midpipe
Any recollection of the torque numbers? On any piston car I've owned, a wide open exhaust has a tendency to reduce torque and therefore street-ability as well some. Was this with a stock or fairly stock motor and boost?
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Old 12-17-18, 05:21 PM
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Originally Posted by Donovan View Post
Any recollection of the torque numbers? On any piston car I've owned, a wide open exhaust has a tendency to reduce torque and therefore street-ability as well some. Was this with a stock or fairly stock motor and boost?
opening up exhaust will get the turbo spooling faster. Really, the best exhaust after the turbo is probably no exhaust, but you of course couldn't drive that without catching stuff on fire.
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Old 12-18-18, 05:11 AM
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OP, what caused your engine failure?
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