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pepere
03-19-1998, 08:22 AM
Last night I went to Cole muffler and had them install a custom catback consisting of a "non-crimped" pipe from the cat to a Dynamax free flow muffler. Cole did an excellent job on the installation. The system works great from 3,000 RPM on up, but has an incredible resonance from about 1800 to 2400 RPM. The resonance was there before, but now it is brainscrambling (my guess is 100+ dba). It would not be so bad, but the auto trans wants to run at 1800-2400 RPM at any speed under 60 MPH. Lesson is: if you have an automatic, be wary of installing a catback. The guy at Cole said that the muffler would get a little quieter as deposits build up in the muffler. If it doesn't quiet down, I probably will reinstall the behemoth stock muffler (without the resonator). Anyone out there got any other ideas?

Mike K.
03-19-1998, 10:07 AM
Pepere,<br>A good friend of mine, who is a very experienced mechanic gave me some advice before I went and changed my exhaust system. Apparently the resonator immediately after the cat is intended to remove "booming" or "resonant rumbling" from the exhaust. That is why, when I replaced my stuff I had them remove the pipe immediately after the resonator (i.e. crimped section) and replace from there. I also used a FlowMaster muffler which is a "free-flow" also, but NOT straight-thru. It is constructed with resonant damping chambers that also reduce noise and create a vacuum as exhaust goes in and out to suck the exhaust out. Anyway, even at the ~2000rpm range my Z has a nice VVVvvvvoooooommmm sound but it is not deafening.<p>Mike K.<br>'98 2.8 B.Grn/Tan/Black - Cone Filter/Dinan Chip/FlowMaster Exhaust (not too loud!) - other goodies<p><i>: Last night I went to Cole muffler and had them install a custom catback consisting of a "non-crimped" pipe from the cat to a Dynamax free flow muffler. Cole did an excellent job on the installation. The system works great from 3,000 RPM on up, but has an incredible resonance from about 1800 to 2400 RPM. The resonance was there before, but now it is brainscrambling (my guess is 100+ dba). It would not be so bad, but the auto trans wants to run at 1800-2400 RPM at any speed under 60 MPH. Lesson is: if you have an automatic, be wary of installing a catback. The guy at Cole said that the muffler would get a little quieter as deposits build up in the muffler. If it doesn't quiet down, I probably will reinstall the behemoth stock muffler (without the resonator). Anyone out there got any other ideas? <p></i>

pepere
03-19-1998, 10:38 AM
<br></i>Thanks, Mike K. The Dynamax is not a straight through either, so it might not be the problem. You are probably right about the resonator. I'll let you know how it turns out.

Greg Hudson (Melbourne Australia)
03-19-1998, 03:54 PM
<br>: Last night I went to Cole muffler and had them install a custom catback consisting of a "non-crimped" pipe from the cat to a Dynamax free flow muffler. Cole did an excellent job on the installation. The system works great from 3,000 RPM on up, but has an incredible resonance from about 1800 to 2400 RPM. The resonance was there before, but now it is brainscrambling (my guess is 100+ dba). It would not be so bad, but the auto trans wants to run at 1800-2400 RPM at any speed under 60 MPH. Lesson is: if you have an automatic, be wary of installing a catback. The guy at Cole said that the muffler would get a little quieter as deposits build up in the muffler. If it doesn't quiet down, I probably will reinstall the behemoth stock muffler (without the resonator). Anyone out there got any other ideas? <p>G'Day Pepere.<br>I hope you read my Exhaust Report BEFORE you made the cat-back mod. If you did, you would have read about how LOUD it was at low revs. (Brainscrambling is a good word for it BTW). I know exactly how you feel, however having a manual, and a lowly 1.9 at least I can 'play' with the revs to keep the beast out of the 'scramble' zone.<p>Now you know why I have the flange, and can simply tear off the stock, and install the Turbo muffler in 5 mins....<p>The important question however is... Have you noticed any improvement in POWER ?<p>I will be very interested to hear what you think of the stock muffler without the resonator...<p>

Greg Hudson
03-19-1998, 03:56 PM
<br>: <br>: Thanks, Mike K. The Dynamax is not a straight through either, so it might not be the problem. You are probably right about the resonator. I'll let you know how it turns out.<p>Pepere. I beg to differ with Mike's comment. Mine has the resonator still there, and it still BOOMS....

pepere
03-19-1998, 04:54 PM
<i>: Did you eliminate the "crimped" section?<p><br></i>

pepere
03-19-1998, 04:57 PM
<Unfortunately, I did not read your report before I modified. I'm going to put the resonator back on first. If that doesn't work, maybe I'll try a flowmaster.<p></i>

Greg Hudson
03-20-1998, 03:48 PM
<br>: : Did you eliminate the "crimped" section?<p><br>G'Day Pepere.<br>Yes, I've eliminated it entirely, however if you go to the following link, you'll see the complete story.


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