Hi folks, can anyone offer some advice on how to quieten the exhaust on a 67 conv. with the factory side exhaust. It's great for the first 30 minutes but gets old on extended trips. I like the looks and Don't want to go with fear exhaust. I looked once for someone that makes a quieter side pipe and was unable to find anybody. Any help will be greatly appreciated.

 

There is no such thing as quite side exhaust just some are louder than others.

There are some members that have added under car exhaust with their SE with electric cut outs to switch back and forth from loud to quieter.
Their under car exhaust exists under the car.

 

Check out classic chambered, he makes several configurations of sidepipes, one may help.

 

2" core VettePacks are the quietest.

 

R - Since GM stopped making their sidepipes years ago, there is a good chance what you have might be aftermarket. Are we talking at least the same configuration of chambered/pinched pipes as the factory used? Do you know if the pipes you have are factory GM pipes or something else? I've got '4' midyears, all with side pipes and three of them are GM pipes, the last one, the 65 396 Roadster I bought a couple years ago has (or rather 'had') a set of nearly new Sweet Thunder side pipes. Externally, they looked very close to the originals, but the sound out of them was obnoxious. Forget about a 30-minute time period to grow disenchanted with them, it was immediate. I sold them to a fellow forum member who is going to dissect them and hopefully make something good out of them.
There are a number of aftermarket pipe makers that claim they have 'original sound' but I haven't heard them myself other than to listen to the customer videos provided by Gardner Exhaust. I talked with two of their customers who were satisfied but as of now, I haven't bought a set of aftermarket side pipes yet for that 65 Bigblock Roadster.
Mike T - Prescott AZ

 

Mike, if I had 4 midyears, three with SE I would be giving my ears a break with number four with a nice quite under car standard exhaust system.

 

Darryl - Been a long time since I had an audiogram but my hearing has always been pretty good and original GM pipes sound good to me but even I kinda draw the line when there's more than an hour of driving involved. I was the kid that used to like to put 'baseball cards' with clothes pins on their bikes so they made this great sound as the spokes made them flutter. And, as the old saying goes..."if a little is good, a LOT is better" so I tried running '2' cards up front.
So, three of the '4' midyears (2 smallblocks, one Bigblock) have GM pipes, I'm still looking around for a good original sounding side pipe for the 65 L78 Roadster.
Regarding the OP's pipes, I'm still curious as to whose pipes those are...GM or Aftermarket? And being aftermarket doesn't mean they're necessarily loud, depends on which particular pipe you're running.
Mike T - Prescott AZ

 

Yes, there are many choices with aftermarket.
I always have to laugh at these posts about how to quite them down.
My complaint about SE (I have owned both a BB and SB with them as well as two C3s with Hooker headers and SE when I was younger) is not only the loud sound but also the lose of power from the 1 5/8 or so exhaust path they have. It seems counterproductive to buy a hipo engine and then plug the exhaust and loose power.
To each their own on this subject.
I did enjoy the SE sound around town when I was younger but never on the highway. I like to have a conversation or listen to music when I am driving.

 

“To each their own on this subject” — Yup , I personally wouldn’t own a C2 without them, but I’m a high performance C2 guy, no creature comforts for me. And you can get them to flow just fine with large cores, however, they won’t be “quiet”….. but they do get the heat away from the drivetrain/cabin better than under-car, and they probably do weigh a little less.

“I like to have a conversation or listen to music when I am driving” — , I can respect that, but both of those considerations would be at the absolute bottom of my list, but as you said, to each their own :-), we all use/enjoy our cars in different ways.

 

I personally wouldn’t own a C2 without them, but I’m a high performance C2 guy, no creature comforts for me. And you can get them to flow just fine with large cores, however, they won’t be “quiet”….. but they do get the heat away from the drivetrain/cabin better than under-car, and they probably do weigh a little less.


Here's a screenshot from Classic Chambered Exhaust's website:


I'm still waiting for some dry weather to have their 2-1/2" ID Vettepacks installed on my L76. These have a 3-1/2" OD and will still fit under a C2's side exhaust covers. I'm not looking to make the exhaust quieter, but I'd really like to improve the sound of my current sidepipes. They sound OK with light throttle chugging around under 2500, but to me they sound awful when I jump on it. The tone of our 68 Mustang convertible exhaust was noticeably improved with a deeper throatier sound when we changed from a 2" Flowmaster exhaust to a 2-1/2" exhaust system with 2 chamber Flowmasters and Tri Y headers. Hopefully the 2-1/2" Vettpacks will sound as good under heavy acceleration - OK, heavy acceleration for a small block. I'm hopeful that any horsepower loss from the stock sidepipe mufflers will be minimized if not eliminated. I'll post an update after I get them installed - hopefully sooner than later.

 

Let me start from the beginning, which is what I should have done, right? When I originally bought the car nearly forty years ago, it had original GM side pipes. Thinking that they were too loud, I had an exhaust shop weld 2 glass pack together thinking that would tone it down. I really couldn't tell much, if any, difference. In 2016 I bought a set of 2" side pipes from Classic Chambered in Michigan. Again, not much difference. After reading all of the posts offered by you folks ( which I greatly appreciate) I think I am understanding that the old original GM pipes were probably the quietest. Am I right? I understand that they may not flow the best but that's not a big concern to me. Again, thank you all.

 

It's true, it's not easy to chose which pipes to go with. I've had the 65 NOM 396 Roadster since November of 2019 and knew even before it got transported home that the aftermarket pipes on it had to go. That was the easy part, finding a suitable pipe that, to me, has similar sound qualities as the original pipes is the harder task. There aren't that many companies making these pipes, which is to be expected, and with Allens now out of business...so it seems, there's one less than before.
A company I checked into about a year ago offered pipes they claimed produced the same sound as the factory pipes, Gardners Exhaust. Contacted them and saw some of the videos from their site of folks with Bigblocks with their pipes. One customer was back in Rhode Island, as I recall, and here's the video they have posted on their site. Now, we all know that pics showing colors can be off at times, not a true representation of the real color, same goes for videos and sound reproduction. The video sounds good and when I asked if Gardners could put me in touch with the customer to talk directly, they obliged. He and another customer out West both were helpful and said they were pleased with their Gardners pipes. They also thought they were very close but maybe not 'exactly' the same sound as factory pipes but again, were happy with their purchase.
I don't know of anyone anywhere near me that has Gardners pipes so all I have to go on are these testimonials. One issue with Gardners products is that they are pricey.
Keep us posted if you do come across some vendors pipes that work for you.
Mike T - Prescott AZ

 

Good question….. I hear you can get the copies of the original Walker/GM design, with “the addition of” ceramic mat/sound deadening added?. See below.


And then there is the “super quiet” configuration?




i’d call the manufacturer and ask, re what is quietest ….. at least you’d know the quietest this particular manufacturer offers

 

I don’t know about availability of Walker SE’s for the C2, but look into them if so. I listened to all the best mufflers for my old C6 GS with long tubes & the factory GM dual-mode Walkers still sounded better than all others, imho.

 

Put in an exhaust crossover. I'd suggest an H pipe kit from Summit or Jeg's but my guess is those wont fit factory side pipes. You may have to get your friendly muffler shop to make one for you. You will notice the difference in sound and a seat of the pants improvement in throttle response.