GHOSTOWLGRID

My cars got an olds 455 in it. Stock with a comp 268H cam.
At first I had magnaflow turbo mufflers and they were like having straight pipes.
I bought walker Quietflow SS mufflers and they make it drivable for daily driving but I am still concerned its a bit loud at night time.

2.5 inch in and out.
At least 18 inches long. Prefferable 20-22 inch long mufflers?
Double offset opposites.
Oval shaped.

I keep looking online for something to silence my car but so far no luck. What do you suggest?
The quieter the car, the better.

I know it will hurt airflow but I was considering getting cutouts for when I take it to the track.

Just a side thought. But I was considering using a crossover pipe like the olds 307 had from factory for single exhaust with converter. But I don't know if a 455 big block ever had a pipe like that, I cant find a pipe that fits.
I was considering single exhaust 2.5 inch with two mufflers in line to quiet it.

marxjunk

walker dynomax super turbo mufflers.....i put them on every convertible ive ever owned...lots of power...pretty quiet..and configurations....no drone

truckman5000

I have these, I love them but have 500hp without headers, there loud but not resonating enjoying.
my dad has a stocking 445, with headers, flowmeter delta? Mufflers, there quietest ones. Those are probably something to consider.

GHOSTOWLGRID

Thanks for the suggestions. I will look into them.

joe_padavano

The Dynomax Turbos are louder than the QuietPower mufflers.

Olds64

Go to a local exhaust shop and tell the owner your desires. It's their job to know what muffler will best fit your car. They will probably be stoked at getting the chance to do the exhaust on a classic car. They probably spend most days welding catalytic converters on late model sedans and exhaust trumpets on imports.

Don R.

Good advice from Olds64. My exhaust guy built a system for my Starfire using IMCO SL422 mufflers, great mellow sound with no drone, could be made even quieter with the addition of resonators.

Allan R

I put resonators behind my dual exhausts and it's noticeably quieter. Also helps if you have good sound insulation behind the rear seat back.

GHOSTOWLGRID

Will do. I have priced a few local places for general cost of a full stainless setup and I think it was 2k for a rough estimate. I'm saving up, I was hoping to maybe find some info on my own and maybe collect some parts online to help decrease costs of parts by getting stuff on sale. The one place I talked to said they can work with existing or prepurchased items. One place quoted 10k to me for the job and I said no thanks. lol

Do you think a single 2.5 inch exhaust and a crossover would hurt the flow of a 455? Price wise it costs less and I can always do a single with the manifold-to-manifold crossover and have the other pipe under the driver side done later. (I have single w/crossover pipe style exhaust manifolds).

I like the photo of your mufflers. I see you have an H pipe welded in. Is it necessary to have that?
At the moment with what I have its separate and no H or X pipes.

redoldsman

At 2k I don't think they want to do your exhaust. I understand that stainless is going to be more but that is a lot. You were more polite to the guy that quoted 10k than I would have been. The single exhaust will be very restrictive and you will lose power. I used an H pipe on a 72 Cutlass I had to reduce drone. You might go the Walker Dynomax website and check out the different mufflers. They have sound clips of each muffler. You might also talk to Waldron Exhaust. They are good folks and can build whatever you want.

GHOSTOWLGRID

Ok. Didnt know the H pipe reduced drone like that.
I will look into Waldron exhaust.
The one thing I cant do myself because I dont have a welder is the pipe for over my axles.
Do you happen to know if I sent them a 2 inch pipe could they reproduce it in 2.5 without the car?
Maybe also make a mirror image of it for the left rear too?
On my cadillac it goes from muffler then over axle and out the back.
I have a new 2 inch pipe from before I decided to do my 455 stuff and never used it, maybe I can send that somewhere and they can reproduce it in 2.5 inch stainless? If I had that I could install it myself after.

Someone else above mentioned resonators. I was thinking I can try them after my current walker quietflows before I have something else done.
Maybe even one of them round cylinder straight through mufflers that I stumbled upon?

Olds64

That's a bummer that you got ridiculous quotes. $2k does seem high. I spent $700 a few years ago on the exhaust for my 71 98. That was duals from the headers to the exhaust tips. It included an X pipe but I provided the mufflers. It was aluminized pipe, not stainless.

Good luck figuring it out. Let us know what you decide.

oldcutlass

Why are you hooked on stainless? Who are you trying to make it quiet for, you or the outside world?

redoldsman

I think you are making this thing way too complicated. I have a Dynomax Super Turbo on my 2012 Expedition and I barely notice it. It certainly is not loud by then it is not a modified 455. If you want quiet, go with their Quietpower mufflers. If they are too loud you and add resonators but I doubt you will feel the need to do so. I think your best bet is to shop for another local muffler shop. They can make all the pipes to fit.

Ozzie

You have many good suggestions. Follow up and do your "homework". Lots of knowledge on this subject is crucial to get the results you want. You may have to do a lot of "looking around" to find the right shop. Knowledgeable personnel are needed. A talented person can create pipes to satisfy your desires up to the diameter limit of his bender, including stainless. Run from the overpriced estimates.

marxjunk

a 2k quote means they dont want to even do the work...

but if youll pay that they will..but you will never be satisfied.

i bet you could buy every piece of that system, in mild steel from a walker dealer..youd be surprised whats available...and walker was an OEM supplier...

dont get confused on hype and what works..2 1/2 is nice but prob 2 1/4 is more than enough with good mufflers for a street car...

or get on amazon and keep checking, they have clearance sales and can get a system for 70% off..the flow master american thunder set, with out mufflers are cheap, just add your mufflers...any shop can install it, they charge X$ dollars an hour and you will be happy... 2 1/2 mandrel bent with no mufflers are cheaper to buy in a kit than to have them bent....they are pretty universal and work 68 to 72...theres even a company that makes 2 1/2 down pipes for stock Olds manifolds for systems like the american thunder...a little research will get it done

marxjunk

Disclaimer..i just hurriedly searched this..so im not sure the #s are 100% correct..but i wanted to give you an idea what it can cost...research your own numbers..its just "an example"

all of this is on amazon..10 minutes and heres your exhaust...i didnt have time to get it at 2 1/2..the pipes i listed are 3 but when i get home tonight i will look some more

68-72 Olds 442 2.5" Downpipes 2 Bolt DOF10S Condition: New $146.49 from Pypes

this is 3 in, but 2 1/2 is available, i dont have time to hunt for them

Flowmaster 1040 Header-back System - 3.00 in. Dual Rear Exit - Pipes Only No Mufflers $ 310

Walker 22266 Quiet-Flow Stainless Steel Muffler $ 36.83 each

thats $530 i have prime and its all free shipping..i believe its free for everyone over $300...

i cant see it being more than $300 to install the stuff..the pipes are so nice they slip right in ive put 20 sets on over the last few years...

Local Hero

$2K is highway robbery. $10K should require a lifetime jail sentence with no chance for parole.

You'll always get the best results when a shop custom bends the pipes to fit your particular car while they have the car on their lift. Then you can have them do the tailpipes the way you want with turndowns, chrome extensions, or whatever your heart desires.

I wouldn't choke down a 455 with single exhaust.

Stock mufflers will be the quietest. An H or an X pipe will quiet it down some more. Resonators will quiet it down even more.

Everything on top of a straight dual set-up is going to cost more. H or X costs more, resonators cost more and so on.

If price is an issue, start with a standard set up. An H or an X can be added later. Same goes for resonators.

The last custom system I had made up was on a 77 Pontiac Grand Prix. Granted this was 10 years ago. But, I supplied the cheapie Summit Turbo mufflers ($19 a piece) and they bent the 2 1/4" aluminized pipe from the manifolds all the way to the rear bumper. It was $250. Stainless would have been $100 more they told me.

Personally, I don't think stainless is necessary especially since cars like these don't see winter weather. Heck, how many of them even see rain?

Regardless, that Grand Prix was a daily driver in all weather that Northeast Ohio can offer, including the harsh winters, and that aluminized system lasted just shy of 10 years before it started rotting way.

GHOSTOWLGRID

I will consider the aluminized. I was asking about stainless because I assumed it lasted longer than alumanized.