Removing the cat. converter, what sound can I expect? - BMW Forum - BimmerWerkz.com
3-Series (E21, E30) Chat relating to the BMW 3-Series from 1975-1983 and 1984-1991 line. Specific models: BMW 315, BMW 316, BMW 318, BMW 318i, BMW 320/4, BMW 320i, BMW 320/6, BMW 323i, BMW 320i. E30 Family models include: BMW 325e, BMW 325i, BMW 325is, BMW 325ix.

 
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#1 (permalink) Old 08-03-2006, 11:00 AM
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Removing the cat. converter, what sound can I expect?

Hi guys!!

I just bought my firts BMW a couple weeks ago, it's a 91 325ix, and since then I'm trying to figure out a way to hear the engine a little bit more. I've searched a lot in the forum trying to figure out wich way I'll go. A performance muffler would be to loud for me and I really like the way the stock muffler looks, so I'm thinking about removing the cat.

The question is if it would sound like a fart can or it I'll be a nice deep raspy sound??
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#2 (permalink) Old 08-03-2006, 03:43 PM
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how are you planning to remove it? It's built into the midpipe so you'd have to have it modified at an exhaust shop. You're also going to make that car smog illegal if you do that. Just a heads up. Personally I'd go with a muffler.


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#3 (permalink) Old 08-03-2006, 05:39 PM
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factory cat muffles alot of sound, ive been warned that with my exhaust if i remove my cats and put aftermarket it gets almost deafeningly loud..

removing them entirely, even with factory muffler would prob make it louder.. but a can is prob just the way to go, the factory muffler , muffles too much lol.

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#4 (permalink) Old 08-03-2006, 05:48 PM
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Hehe... you guys and your smog problems. They don't check any of that stuff here in KY. They used to have some bull shit emissions testing in L'ville called the VET test, but it was nothing but a racket to make money for the city and they voted it dead finally a few years ago. But anyhow, everyone around here just cuts them out and welds in a straigt pipe if they want. You can't get most exhaust shops to do it as it is illegal but if you do it yourself, no one ever checks it! I just took my down pipe section down and cut the cat off as close to the cat as I could and welded a new bolt flange to the pipe. Then I took a section of pipe the exact length of the cat that I removed and and welded two more flanges to that pipe. This way you can put an aftermarket cat back in with minimal effort later if you had to sell it to somewhere that they had to have it, plus having a removable center section makes taking down the system much simpler later on. As far as the sound, you should like the difference it will make. It will pretty much just amplify the sound you already have.
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#5 (permalink) Old 08-03-2006, 06:30 PM
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I already have the guy to do the work and for the emissions thing, I've had two cars without cat, a 92 civic hb and a 93 SE-R and both of them passed emission test, even with aftermarket stuff.

BTW. I'm in Puerto Rico

thanks for the input..
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#6 (permalink) Old 08-03-2006, 09:55 PM
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I would just go with a nice exaust thats not too loud, they exist. Also a cone air filter / heat shield will give it a sexy sound also, and give you a little bit of HP with the exaust.

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#7 (permalink) Old 08-03-2006, 10:41 PM
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If you remove or gut your cat you'll get more of a Blahhh sound (think annoying punk honda). I just put a basic thrush turbo on (about $20) in place of the muffler and now it's got a decent growl. When I go turbo, I'm getting a high flow cat, I'd just as well have my car run cleaner anyway.

P.S. It is against federal law to gut or remove your cat. Junk yards can be fined up to $50,000 if they get caught selling a use one.

Last edited by Starmavin; 08-03-2006 at 10:45 PM.
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#8 (permalink) Old 08-04-2006, 09:47 PM
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what I used to do when the cat was removed on my previous cars was putting a cherry bomb resonator to prevent the fart can noise and a performance muffler. But if do this in this car is going to be a lot of work and double the money making a resonator fit with the exhaust plus adding the new muffler.

BTW does trush mufflers come with double inlets??
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#9 (permalink) Old 08-04-2006, 10:18 PM
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Quote:
Originally Posted by Starmavin
If you remove or gut your cat you'll get more of a Blahhh sound (think annoying punk honda). I just put a basic thrush turbo on (about $20) in place of the muffler and now it's got a decent growl. When I go turbo, I'm getting a high flow cat, I'd just as well have my car run cleaner anyway.

P.S. It is against federal law to gut or remove your cat. Junk yards can be fined up to $50,000 if they get caught selling a use one.
And yet they can sell you a whole midpipe no problem.


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