Hi all,

I've got a 10.5:1 355 going through some 1 3/4" primary long tube headers into a 3" pipe and the worlds smallest muffler, then dumping under the rear bumper. I have no idea what the muffler is, but it's literally 6" long, 4" tall, and 8" wide, and couldn't muffle a gnat's fart at a Metallica concert.

Starting this car sets off car alarms nearby. People have heard me and called me on my cell phone before I could see their house. It's loud. I've got a cutout I can open if I need loud and/or fast, but for daily use, I want *quiet*.

I'm driving from Michigan to Seattle in about 6 weeks, so I want the absolute quietest 3" single in/out muffler I can get. If it reduces me to an 22 second 1/4 mile, but is so good I have to check the tach to see if the car is running, that's perfect.

Help me out folks, my ears (and sanity) are in your hands.

 

Drive down to the local muffler shop and tell them to put an RV muffler on it.

 

That's the first I've heard of an RV muffler, but I like it. Are they huge, or just really effective?

EDIT: Holy Jeebus they're huge. Dynomax Super Turbo RV is 8 1/4" round by 36" long! I don't think I have that much space between my axles! But I shall go measure, just in case

 

Where the current muffler is, I can fit an 18x12x6 replacement. I don't have much clearance under the car before the axle, but I could probably fit a glasspack there if it would help with the noise?

 

Just discovered another issue. I'm missing half a gasket where the y-pipe joins the down-pipe, so it's blowing hot air like a hair dryer there. Still want the car dead-quiet though!

 

I can't remember where this came from but maybe it might help. The quietest at idle are Borla XS and Hooker Max Flow. Same at 2000 rpm. Then the Max Flow jumps up at WOT. So somewhere between 2000 rpm and WOT, the Maxflow gets loud.

 

Is that the same as the Borla ProXS?

 

The Edelbrock RPM muffler listed on there doesn't exist any longer, it's been replaced by the SDT muffler (like a Flowmaster) and is LOUD AS HELL! The 3" exaust on your car is the biggest culprit next to the muffler. You can only get it so quiet with pipes that big (see the "backpressure" sticky).
The Borla part number for an OEM fit is 40474, and I found them cheap here -
http://cgi.ebay.com/ebaymotors/ws/eB...MakeTrack=true

 

I would look for something off of a Cadillac. I think using a "pre muffler" might help to get it really quiet. If you have to you can use 2.5 pipe on the muffler the exhaust gas isnt as hot there and doesnt need as much volume.

 

I read the backpressure sticky, but didn't see anything about volume, just the resonance freq for performance. Maybe a pre-muffler from 3" to 2.5" and out to another quiet one mounted in the stock location?

 

That would be my best idea for something really really quiet. Maybe some one else has a better idea?

 

I think I identified my mystery muffler. I had been told it was a 40 series flowmaster, and since this was my first muscle car, I assumed all 40 series were that loud. It actually appears to be a Flowmaster Delta Force 1 Chamber Race Muffler. "For use in race applications requiring mufflers but without set decibel limits"

 

Yeah, I'll bet the neighbors are loving your car! LOL

 

Their car alarms sure notice it! Always felt bad about setting the alarm off at 7am every day when I left for work.

 

Both my car and my truck are that loud intentionaly. Its fun going through parking structures, I can set off alarms several floors up and down if I rev it up a little. I will agree though after a while being loud gets kind of old, Ive been debating quieting the truck down being that I drive it everyday. I was told the same thing the RV muffler is the quietest but its huge. stock replacements from a v8 truck arent to bad, there about 24" long and 8" in diamater, but most are only 2.5 pipe in and out.

 

SLP's dual-dual muffler (came factory on LS1 camaro/firebirds equipped with the optional "dual dual" exhaust but still required to meet new car sound limits) is worth a look. It's free flowing (the LS1 guys rarely notice a difference when they remove this muffler for a different one, even on the dyno) but _very_ quiet (most LS1 guys change it to get something louder/more aggressive).

I have one on my L98 and am very happy with it. Happened to pass the local law enforcement at WOT once and didn't get pulled over. what more can you ask?

In my opinion it's slightly quieter than the Borla Pro XS, which is also pretty quiet.

Both are much quieter than the flowmaster 80 series

 

Thanks for the suggestion, but the exhaust I've got now is a single 3", and I don't want to replace the whole thing if I don't have to.

A couple guys at work have recommended dynomax super turbos as very quiet. I think I'll probably put one of those on with a short turndown, and if it still needs to go quieter, put in a pre-muffler too.

Thanks guys!

 

A bit off-topic, but if there are laws against exhaust notes at high dB's, then why are people allowed to blare their rap music to the point of violently shaking people's mirrors and windows of nearby vehicles?

 

super-turbo is a wise choice. They flow great.

 

That was a 'Stang site. Used dual 3" for each test, ~300 RWHP if memory serves. That was a wicked series of tests to run, but the results were very telling. The Borla took the cake for noise (that being louder is worse) and power. The only muffler that made more power than the Borla was the Warlock uncorked (better than uncorked headers). Corked, the Warlock was amoung the worst for power, and still noisy (I happened to have Warlocks at the time, so that was particularly significant to me).

I don't believe what they tested was technically the ProXS. Also don't know if there's a significant difference, or if Borla just changed the name for marketing purposes. Their site says ProXS is only available from authorized installers.

 

92-94 caprices use a muffler and a glasspack(i have one) to quiet them out so, the "pre" muffler will definately work.