Gutted cat muffler question
08-13-2018, 07:19 PM
#1
Burning Brakes
Thread Starter
Gutted cat muffler question
Somebody gave me a gutted 951 cat, so I'm wondering 1.) how loud it would be vs. stock cat and muffler, and; 2.) what muffler (if any) would make such a gutted cat decently quiet but still efficient.
Can anybody here tell what works with gutted cats, and what doesn't? Is it worth messing with?
Can anybody here tell what works with gutted cats, and what doesn't? Is it worth messing with?
08-13-2018, 08:42 PM
#2
I had a gutted cat for many years.....personally I loved the sound it made. this was with everything else stock except a chip. Not much louder at all IMO until you take it to redline and then you want it to sound louder anyway.
my two cents
my two cents
08-13-2018, 08:49 PM
#3
Three Wheelin'
I gutted my cat years ago... Had factory muffler, was quiet... Now I have a magnaflow still quiet, I made it so that I could take the Magnflow off and put a straight pipe, Then its loud! LOL... (All 3") back..
I keep the muffler on now because its just a street car, and I have a purpose built track car. I build the same sort of system for the track car in case I have to go to tracks where there is a DB limit... it has 4" on it. Way louder than the 3"
As far as "worth" the first time i gutted a cat I took the rear section off, Smashed the Ceramic with a steel Rod, Started the car up (blew ceramic all over the garage) and I was Done! Bolt the back section back up... so its super EZ
I keep the muffler on now because its just a street car, and I have a purpose built track car. I build the same sort of system for the track car in case I have to go to tracks where there is a DB limit... it has 4" on it. Way louder than the 3"
As far as "worth" the first time i gutted a cat I took the rear section off, Smashed the Ceramic with a steel Rod, Started the car up (blew ceramic all over the garage) and I was Done! Bolt the back section back up... so its super EZ
08-14-2018, 04:29 AM
#5
Burning Brakes
Thread Starter
Well, since my muffler has seen better days, what sort of Magnaflow or other works well?
Is this just a case of saw off the old muffler, clamp on a Magnaflow, and done?
Is this just a case of saw off the old muffler, clamp on a Magnaflow, and done?
08-14-2018, 08:26 PM
#6
Three Wheelin'
Pretty much.......... I chose the magnaflow because It was available just down the street. Note your ID /od, I assume you can hack the old muffler off and slide a new one on. You will still need the "Tip" and small section of pipe after the muffler to complete it... Look it over, Measure and then decide...
08-15-2018, 08:49 PM
#7
Drifting
I wish I had installed the muffler myself... something about the ‘cut & weld’ I’m not crazy about. Oh, and the Magnaflow is far lighter than the original. In fact, I should have kept the original; it was only the tailpipe that was corroded.
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08-16-2018, 03:05 PM
#8
Burning Brakes
Thread Starter
951 stock muffler is a “straight through” type; the pipe just goes straight through and the muffler surrounds it. I had a shop install a similar Magnaflow in Stainless. Sound is pretty much the same except the “boom” moved from 3000rpm / 120km/h to lower about 2000rpm, meaning it’s not at highway cruising speed anymore.
I wish I had installed the muffler myself... something about the ‘cut & weld’ I’m not crazy about. Oh, and the Magnaflow is far lighter than the original. In fact, I should have kept the original; it was only the tailpipe that was corroded.
Regarding the "boom" at 3k rpm going to 2k rpm, am I correct in understanding that it is now quieter at cruising speed?
08-16-2018, 10:04 PM
#9
Drifting
Sorry, I can’t tell which Magnaflow model it is; the shop just picked one from their stock that was of similar size as the original and “straight through” design. It just says ‘Magnaflow’ on it.
Yes, it is quieter at 3k rpm. The stock one had an annoying “boom” at that speed (for lack of a better term) which forced me to either cruise 10km/h faster (speed ticket territory) or slower (not favourable). This one booms around 2k rpm which I hardly notice.
The shop cut the muffler pipe close to the old muffler and welded this one on. The weld is already turning a nice rusty brown. This affair cost me $350CAN. What I should have done is bought a complete muffler (flange-to-tailpipe) from the many stock-type replacements and installed that myself.
There is no resonator per se but the shop guy said the stock cat is actually a resonator/cat all-in-one.
Shortly after this, my wife’s car’s muffler went, so I ordered a Bosal direct replacement, complete to flange, gasket, hardware (spring bolts), and installed myself. Relatively easy procedure. The Porsche got the hack. Never again!
Yes, it is quieter at 3k rpm. The stock one had an annoying “boom” at that speed (for lack of a better term) which forced me to either cruise 10km/h faster (speed ticket territory) or slower (not favourable). This one booms around 2k rpm which I hardly notice.
The shop cut the muffler pipe close to the old muffler and welded this one on. The weld is already turning a nice rusty brown. This affair cost me $350CAN. What I should have done is bought a complete muffler (flange-to-tailpipe) from the many stock-type replacements and installed that myself.
There is no resonator per se but the shop guy said the stock cat is actually a resonator/cat all-in-one.
Shortly after this, my wife’s car’s muffler went, so I ordered a Bosal direct replacement, complete to flange, gasket, hardware (spring bolts), and installed myself. Relatively easy procedure. The Porsche got the hack. Never again!
Last edited by Dan Martinic; 08-16-2018 at 10:07 PM. Reason: Added info
