I did a search but I am still stuck.
I am in the process of restoring a '77 L48, 4 spd. I want to keep it "close" to stock. Since the stock exhaust system will have to be replaced I was curious about my options. I was thinking about true duals. What should I be looking at? Cats or not? Pipe diameter? Mufflers? Where to buy, should I order a kit, or have a local shop "build" something for me? I don't mind it if it has a little sound to it also, I just don't want to get into any mods other than "bolt on". A little help is needed, as this is my first Vette. Thanks all.

 

I just installed the jet hot headers/sidepipes and really like how easy they were to install or take out. Im waiting on the spiral mufflers now which I should get anyday. I also just got done with the 2004r trans. I was amazed on how much weight I dropped off the car getting rid of the stock exhaust and old crossmember and putting on the sidepipes and bowtie crossmember. I wanted something I could put/take off when needed also like the look and its all just bolt on. I cant comment on the sound till I get the mufflers,I hope its not going to be to loud but what I can say is it was a easy install and looks great.

Just something else to consider for exhaust option

 

Having a "good" shop install a new system you can't go wrong. Most shops now sell & install performance muffles like magnaflow & flowmaster. Headers are an option its up to you but they are not going to give you that much hp's for the money spent. True duals, 2.5" in dia a crossover or H pipe and performance mufflers will do the trick. Cats are necessary for state inspection. If you have QQ plates then you don't need the cats.

If you like to work on your own car you can buy everything mentioned above from one of the vette vendors. Most will give you a 10% discount just for being a forum member. Here are a few incase you don't know, Mid-America, Corvette Central, & Ecklers all have what you need/want & will give the 10% discount.

Hope this helps. G/L

 

I have a '77 L48 4spd. too. The previous owner did the exhaust from the manifolds back. 2 1/4" true dual, no cats, to 40 series Flowmaster and big chrome tips. Having also had a truck and Z28 with Flowmasters, I'm getting rid of 'em.... and the big chrome tips too. Dynomax mufflers don't create the interior resonance that the Flowmasters do. I'm planning on a h-pipe, dynomax mufflers, and coated headers. As far as what diameter exhaust pipe for dual setup... I'm not sure what is the best. I can't decide on headers either- Dynomax, Hedman Elite, Hooker long tubes, Stan's??? Spend the extra money and get the ceramic coated headers.

 

PM sent

 

Exhaust is such a personal preference it is hard to recommend, however; I installed the chambered exhaust setup on my 77 L48, and I think it is too loud. It would be good on a '60s car, but doesn't match up with the 77 year group. I have sidepipes on my 68 and it sounds good. I think I am going to get mufflers and install them in place of the tailpipes on the chambered exhaust. Trying to decide on what mufflers to get now. You will need a converter unless you are going historic or classic with your registration. For what it is worth. Cheers.

Tommy

 

I have a '78 L82 and went with the true dual exhaust from Corvette Central. It fit great...no problems. Sounds great and freed up some horespower and the car ran better afterwards.

A lot depends on your state laws. I'm in Maryland and after 25 years, the state doesn't care and it doesn't have to undergo emissions testing. Check your state laws and see if you're still required to runs cats.

 

See what many refer to as my Exhaust topic.
http://www.corvettefaq.com/c3/ganeyexhaust.htm

 

Thanks all.
Jims79: What are QQ plates? In Florida we no longer have inspection. (It was a scam anyway).
Noonie: Thanks for the local info.
Ganey: Thanks for those numbers. That looks like it makes a big difference for a bolt on mod.

If I delete the cats and go w/ duals and mufflers, what do I have to do on the intake side? Do I need the carb worked/tuned, or the timing adjusted? Also, w/ duals, does that delete the crossmember? I was a two stroke mech. back in the day, and always had to work the carb after instaling a pipe. Thanks for the info.

 

I believe the 77 still had the two holes in the crossmember for dual exhaust. Nothing is required to run this setup (i.e., intake change), but anything else you do to free up the air, such as replacing the intake with a better intake, will allow better flow.

 

Yes, the '77 has two holes in the crossmember. You can use a 1974 dual exhaust system, as I did on mine...

Good Luck

 

Have 78 last year was in same place you are..... went with covette central, duals, with hide away oval mufflers.. sound good, easy to install (if you doing the work yourself)...Save some bucks to put into some soft leather.....Think it olny cost me about $280. this was all pipes clamps, muffles, hangers included, nice package. I think the standard/auto ( liitle diff in pipe bind) same cost.....

 

Have you considered these guys?

http://pypesexhaust.com/

They have a complete system with x-pipe that I am considering.

 

I went with this in 2 1/2" and Magnaflows. They make this conversion to fit '75-'79 only and it looks factory. Fit is perfect. And if you do it yourself it will run $306 plus shipping............

 

I installed true dual exhausts from Corvette Mid America on my 75. The fit was a problem and I had to take it to a muffler shop to bend things a little to get the right better. It still doesn't fit quite right and I had to wrap the exhaust pipes with header wrap in the vacinity of the auto trans as the pipes run very close to the tranny and I was afraid of the heat that close to the tranny. I didn't put on dual cat's and that was a mistake --- you get a noxious smell from the exhaust if you stand behind the runing car if you don't have cat's.

My suggestion is go for the true dual exhausts. Order the parts and Have a muffler shop install them for you. I guarantee you if you try to do this yourself it will turn out to be a real hassle and you won't have the tools and supplies to get it done right. Put on dual thru-flow cats. Lastly, don't let the muffler shop weld the pipes together (like I did). Rather, have them use U bolts like everybody else to connect things together. That way if you need to move things around or you want to change mufflers or you need to drop the exhaust to replace the rear spring, you don't have to cut your exhaust system apart. I guess you can tell, this conversion didn't go smoothly and I had to fiddle-fart around with this system for weeks before I got comfortable with the look, the sound and the safe control of the heat. My 2 cents from experience

 

We, "The wife and I" have 2 77 Vettes, one a 4 speed and one a auto. A duel exhaust for a 74 will bolt right on with the addion of a bracket that mounts to the trans mount, just forward of the crossmember. As for installing it yourself. If you cant do something this simple you just cant work on cars. It's a PITA. But it's just bull work.

 

Just for an example my old muffler shop left side head pipe was a straight piece of pipe from the first bend thru the crossmember. The Corvette Central head pipe after the first bend had three more BEFORE the crossmember! Without all the right bends this job can be a real pain. And after I bought a $20 die grinder I only had to cut the old pipe once on each side to get it out.

This system is so easy to install a caveman could do it.................

 

i have a complete system that sounds really good. i will be removing it soon to install the headder sidepipes i just got. it will be for sale. the stock manifolds were ported out to a d-port felpro 1406 gasket.

 

What is everyone doing for carb re-jetting or tuning after installing the true duals?

 

If you have the stock carb and manifold, You will need to do some drilling to your idle tubes and low speed mixture ajust screw holes. P.M. me and I can send you some spec's. Let me know your whole combination. compresion, air filter, cam etc.