CRAZY LOUD EXHAUST

[lakeside]

I have Kooks LTH with an off road H pipe going to stock Saleen Magnaflow rear mufflers. Car has FR Hot Rod Cams and a Roush Blower. At first the "in your face" loudness was kinda fun, but it has quickly become obnoxious. Has anybody documented power difference between Kooks Catted H mid pipe and their Off Road H pipe? Or does anyone have a suggestion on how to tone down the Blatty/Trumpet noise.

 

[Pentalab]

Do you have any drone around 2k rpm ? I installed JBA LT's, and a catted H mid section....and also FRPP FRS-500 mufflers. Bad drone at 2k rpm. WAY too loud for my tastes. Fine if at idle, or < 1.5 k rpm. Get my foot into it, even just a bit, and it's too loud, novelty wore off in < 2 weeks. My fix was to weld in a pair of 304 SS Pypes M80's... which are just SS resonators. Had them welded in, just before the rear axle. Problem solved. Drone is all but gone..and overall level was reduced a bunch.

Loud exhaust is one thing, but when I can't hear the stereo inside the car, with windows up, it's over the top. I also have to be able to leave late at night, and come back late in the early AM. Neighbors were pissed off asap, before the resonators were installed. It's still loud, but not obnoxious. Overall pitch dropped to a low freq rumble type of sound, which suits me just fine.

That blatty / trumpeting tone turns the car into a blatmobile. M80's are cheap at AM. Almost any quality resonator will do the job. Instead of using the clamps, I cut the slotted portion off on each end of each M80, then had em welded into place. 304 SS is shiny, and stays shiny after years of use. Resonator's like M80's are essentially like glass packs, just straight through pipes, with the small holes around the circumference on the insides, with the baffling material between outer SS casing and interior holes.

https://www.americanmuscle.com/pypes-m80-muffler.html

 

[lakeside]

Well thanks for the tip, I was thinking about doing the same thing with Borla XR-1 racing mufflers, but $58 for the M80 versus $150 for the XR-1 sounds a whole lot sweeter. Their design looks the same also, except the M80's are polished. The BLAT has gotten so bad that even pulling away from a light slowly with a Prius next to me has the guy thinking I'm trying to race him (not that pissing off prius's isn't fun)

 

[Pentalab]

Well thanks for the tip, I was thinking about doing the same thing with Borla XR-1 racing mufflers, but $58 for the M80 versus $150 for the XR-1 sounds a whole lot sweeter. Their design looks the same also, except the M80's are polished. The BLAT has gotten so bad that even pulling away from a light slowly with a Prius next to me has the guy thinking I'm trying to race him (not that pissing off prius's isn't fun)

The M80's are not a replacement for the muffler's, they are in addition to them. Get em as close to the rear axle as you can, then they are higher off the ground. They get installed on the inboard side of the rear axle.

 

[lakeside]

Yeah, on the Saleen you can't lose the axle back muffler stuff because of the center exhaust without doing a ton of custom work

 

[Screamin_dutch]

The regular magnaflows are a pretty quiet muffler, so youre good there. I would put high flow cats in, im putting mine back because the o/r pipe is insanely loud with longtubes. Start there, add resonators later if you have to tone it down more. They help.

Kenne bell documented the effect of cats on their site, you wont notice the difference. I didnt when I took mine off last week. Just STUPID loud.

 

[06 T-RED S/C GT]

The regular magnaflows are a pretty quiet muffler, so youre good there. I would put high flow cats in, im putting mine back because the o/r pipe is insanely loud with longtubes. Start there, add resonators later if you have to tone it down more. They help.

Kenne bell documented the effect of cats on their site, you wont notice the difference. I didnt when I took mine off last week. Just STUPID loud.

I started out with Magnaflow street mufflers with the stock exhaust. Only negative experience for me was the interior resonance drone between 1500-2000 rpm in 5th gear while at cruising speeds on the interstate. But I'll admit the drone wasn't nearly as bad as with the Borla S-type (stingers) that I replaced the Magnaflows with. Needless to say, I'll be putting both the Magnaflows and Borla Stingers up for sale, as soon as my Roush Extreme cat-back exhaust arrives and installed.

 

[Juice]

Ive seen adding high flow cats boost midrange power significantly and barely cost any HP on the top end.

 

[eighty6gt]

i've seen every high flow cat imaginable melt down and a few royally $#!$ up some high $$ builds

 

[eighty6gt]

..except kooks greentech I think they are about $900/ea - can't find tiger honaker's invoice on here any more.

 

[06 T-RED S/C GT]

i've seen every high flow cat imaginable melt down and a few royally $#!$ up some high $$ builds

Are you referring to ceramic or metallic? IIRC its usually the ceramic high-flow cats that meltdown as they can't withstand the heat from running FI applications.

..except kooks greentech I think they are about $900/ea - can't find tiger honaker's invoice on here any more.

If those Kooks green cats are $900.00 ea just by themselves? Well, they can just keep them, as there's no way in hell I'll pay $900.00 for a catalytic converter. Much better off just buying a pair of Magnaflow high-flow metallic cats and add non-foulers to the rear 02 sensors for passing the OBDII emissions inspection. Anyhow, just my opinion.

 

[eighty6gt]

every single aftermarket cat, ceramic, rock wool, fake, real, imagined

ALL FUCKED

 

[06 T-RED S/C GT]

Then I'm glad I never sold my "OEM" catted mid-pipe. Anyhow, I really thought that an aftermarket metallic cat was far better quality over the factory ceramic cats? Therefore it would appear that I was obviously wrong

 

[Juice]

I ran the BBK catted x on my 91 supercharged fox for many years. Never had an issue. Car makes 420 at the wheels. I have also seen many bone stock family cars melt down cats when I worked for a dealership. You dont need high hp high dollar builds to melt cats.

IMO it is too much raw fuel, ie, a very safe tune to avoid leaning out that kills cats. I have seen ppl trying to limp home with a dead alternator to the point the car is bearly running and the converter is cherry red. (Yes, it was at dusk).

 

[Phil1098]

IMO it is too much raw fuel, ie, a very safe tune to avoid leaning out that kills cats.

I completely agree with this, my daughter had a new Beetle and the car lost one output on the coil pack. Apparently the injector still fired even though there was a dead miss. She drove it home a few miles and it took out the converter. Sounded like it was half full of rocks.

 

[Juice]

I completely agree with this, my daughter had a new Beetle and the car lost one output on the coil pack. Apparently the injector still fired even though there was a dead miss. She drove it home a few miles and it took out the converter. Sounded like it was half full of rocks.

Exactly!
How about the 700 hp Hellcat, or Roush supersnake, or the Supecharged Corvettes? All have cats from the factory and come with a warranty.... Makes you go hmmm

 

[01yellerCobra]

Exactly!
How about the 700 hp Hellcat, or Roush supersnake, or the Supecharged Corvettes? All have cats from the factory and come with a warranty.... Makes you go hmmm

There's safeties built into the stock tune to keep the cats safe. A lot of tuners turn those off which can lead to ruining the cats. I remember BruceH talking about leaving them turned on and not having issues with his cats.

 

[06 T-RED S/C GT]

Hope this doesn't seem like a dumb question, but how do you find out as to whether or not those safeties are turned off or on by the tuner which would be Brenspeed

 

[Pentalab]

Hope this doesn't seem like a dumb question, but how do you find out as to whether or not those safeties are turned off or on by the tuner which would be Brenspeed

ask em.

 

[Pentalab]

Zero issues with my JBA hi flow cats..which are ceramic. Also JBA LT's...+ small roush M90 blower, twin 62mm TB..and 94 tune.

They did some exhaustive tests in the old 5.0 mag, and the difference between hi flow cats...and no cats was essentially zero. 1-2 hp in favor of high flow cats at a narrow rpm range.... then 1-2 hp difference in favor of no cats at a different / narrow rpm range.

With the huge increase in volume with my exhaust setup, the increase was attributed to the high flow cats (or no cats) and not the LT's. FRS-500 mufflers were installed years before the LT's and hi flow cats install. The only fix was either replace the SS FRS-500 mufflers with oem muffler's.... or weld in a pair of SS pypes M80's.

High flow cats work cuz they are bigger diameter than oem.... more parallel paths. But everything gets louder too. The exhaust just reeks on any car I have seen with no cats.