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I have a 1977 L-48. Automatic, air conditioning, etc. It has 81,000 original miles and is TOTALLY stock. I have an appointment at the exhaust shop this Friday. What type of setup for mufflers and pipes should I get to give the best performance and sound? I don't want it to be loud, but I don't want it to sound wimpy! I want it to sound like the muscle cars of the early 70's.

What amount of horsepower gains can I expect with the new setup?

Thanks for your help.

You'll get a lot of opinions on this one. Check out the thread below for a few that have already been expressed. I'm going with chambered exhaust but, judging from your post, that is probably louder than you want. Most of the better preformance systems, including chambered, only sound out when you get into them. Idling and cruising noise is not oo bad with most.

Don't forget local emissions requirements.


There are a number of performance mufflers out there that will work. Probably the most popular ones are Flowmaster mufflers and there are several different models of them depending on what sound you want. I have 40 series Flowmaters on mine and they are fairly loud, with a lot of resonce(sp). This is the humm you hear inside the car at different RPM ranges. Personally I dont care for the resonce being very loud or strong, and would probably go with a different series if I were to change. The Flowmaster web site has all their info on their mufflers.
There are several other good choices also but I don't know much about them so I won't go into it. Someone else can fill you in on what they like.
I don't think you will get much of a performance increase with just changing your mufflers but you may think so from the new sound. It is however a good first step. You can make other changes as time and cash afford.
i have the 40 series flowmasters as well which i like. also, i think its mid america that makes a 2 1/2 stainless steel system that works pretty well. an H pipe also helps with the sound. if i were you i would try to find a way to lose that converter too. i don't know what it does to the sound but it kills power real well.
I have the same car as you - a '77 L48. Some eight years ago I replaced the entire exhaust system, front to back. I asked my mechanic to make sure that the parts were stock.

When I got the car back I discovered that my new mufflers hung down quite low - several inches were visible below the body at the back of the car. I compared this to earlier C3 Vettes and discovered that their mufflers were tucked up under the body. "What's up with that?" I asked my mechanic. He explained that earlier model Vettes had thinner mufflers.

I put up with those mufflers for a while but soon grew tired of the look. I had them replaced with mufflers from an earlier model Vette. Now they can't be seen when you stand beside the car. Much better.

This may not relate to your original question but I don't want you to make the same mistake I made and have your car end up looking terrible. Something to consider.


HP increase, see this: Why Exhaust is problem for HP on 75-81

Dynomax coated headers, duals, crossover & Dynomax mufflers.
L-48 badly needs another cam.


See you already pointed him to the topic.
The chambered is too restrictive. If someone wants chambered, this will help, put the chambered part at the end in stock location.
Mufflers & Exhaust!!!!

Thanks guys for all your help. Will let you know how it turns out.

......interesting. so, where can i buy a pipe to replace my cat?

i don't know of anyone who makes them but it can't be that hard to fabricate at an exhaust shop. its just a straight piece of pipe. depending on what your looking for you might be better off going with real duals.
mga said:
......interesting. so, where can i buy a pipe to replace my cat?

Most aftermarket vendors sell them. They call them "Test Tubes" or "Off Road" use only. Check our Community Vendors Page HERE or the new Portal HERE for a few websites to check out.. Good Luck

I had a high-flow cat installed on my "76 L82 today. Everything is stock and it had the original cat. I have been hearing stories about the tremendous difference this change has made for others and thought I should add my own observations.

I have not had the chance to really test the performance yet, but it doesn't seem to have made a really noticable difference. I would be able to tell better if I had the chance to open it up on an open road. It does rev faster, more like a small block should and seems to feel a little less sluggish. I believe it must be breathing easier. Also, the exhaust seems to resonate more than it did before (I'm not sure why that would be, but I'm not complaining).

Okay . . . call me an Okie . . .

I bought my 'vette with flowmasters installed. My son loved the sound . . . of course, he's only 16 - the louder the better. I was to the point of welding new mufflers on the system.

Came up with a better idea. I found, on the JC Whitney website, baffles that are the correct O.D. for the I.D. of the outlets on the flowmasters. I drilled a 9/32" hole in the bottom of the outlet and the baffles. Makes the 'vette sound nice, without excessive noise around town . . . and with a couple of bolts, I can have a nearly wide open exhaust for the strip!!

Oh, BTW . . . the baffles are actually motorcycle resonators. Just a thought.


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