[Can Am Kid]

Since im on the search for the Carb, i guess its a good time to ask about the exhaust. Old one rusted all off. Right now im running stright off the header, not the quitest thing. The car is all numbers matching and im trying to keep it that way. I dont know if the exhaust is numbered in that sense. Judging by the muffler and Cat that came off of the car, they werent the most free flowing things.

Is it better to get a new exhaust made for the car, or buy one pre made?

[75cancup]

Depending what you want you could get a double hump cross member and run duel exhaust (pypes ofcoarse ) with cats to keep it legal. my.02

[77 Canamman]

Unless you have strict emission laws in your territory, replace the crossmember with a '73-'74 crossmember, and install a dual system. You fuel economy and engine will thank you.

[Brian Baker]

Was able to fit a small (2-1/4") dual exhaust on my Can Am without changing the crossmember. No need for anything larger on a stock W72 400. The cats on it are the small monolythic type, dumping into a pair of 3-chamber FLowmasters.

[77 Canamman]

Brian,

How did you route the pipes? Do you have any pics?

As easy as it is to find and install one of those dual hump crossmembers, I would go that route if you are starting from scratch. It will be a cleaner looking installation.

[Can Am Kid]

I could use pics as well to show the muffler shop how i want it done.

[BR57]

77 Canamman and others who recommend the double hump are giving you the best option for dual exhausts.

I give you an alternative if your state requires the converter and you don't go to the trouble to get the double hump crossmember. We did this on a 75 Cutlass so it should work on the LeMans/Can Am. The 76 Impala 454 came with a dual set up from the factory. It consisted of a Y pipe from the manifolds to the converter to the right side of the car, single hump crossmember. The pipe out of the converter split again and two mufflers set up in the floor pan hump with dual tail pipes. Similar systems used on 78-81
Z28 and some Trans Ams and 85-88 Monte Carlo SS cars.

[CanAm1977]

Hey CA Kid,

If your going to have to replace the exhaust do it in duals ...you won't regret it. Any competant muffler shop can custom bend a set of duals for you even with a single hump crossmember. It's just the passenger side will be a little closer to the ground. I agree with everybody here that you should replace the crossmember with a dual hump one and maybe there's someone out here that has a spare. (anybody help him out)
Depending on if your state does emission testing of your car depends on how it's registered. If you get antique plates your exempt ..... won't even need to put on converters then. If you have regular plates you might need to be tested as most states test all the way back to 1968 model year. You would think that crossmembers from other A body cars would work for you but I've heard rumors that not all A body crossmembers will interchange. You may want to ask for recomendation on which muffler to use. For my 2¢ I think Flowmaster 40 series are to loud. The 50 series is a little more mellow. And also look into the T/A exhaust tips they look sharp when tucked up behind the qtrpanel so that only about an inch or two is exposed. Also in my opinion the tips should be placed further back closer to the bumper rather than right behind the tires. Another option would be to have some tips made up to look like the one from a '73 GTO

[Can Am Kid]

My only thing with flowmasters is that they seem to rust after one to two years. Put one on my truck two years ago and it rusted up pretty nice. I want something thats going to last, even though i dont plan on taking this car out in the winter or when it rains.

About emissions, i think its 20 years till your emissions exempt. So i can do just about anything i want to do to the exhaust. That brings up the question about the cats. Should i put them on or leave them off?

[Brian Baker]

Don't have any pics, but I agree...the clean instal will be with the double hump crossover.

Dude...whomever installed those tips on that '73 got them wrong. The shouldn't exit from under the 1/4 so close to the bumper...that little bend should be closer to the wheelwell where it pokes from under the bumper, with the tips coming just to the bottom edge of the bumper (or a little past).

[billygoatii]

I would install the double hump crossmember (or modify the single hump) and put on a true dual exhaust. If emissions testing is not a concern, I would leave the cats off. If you want the cats, put on a pair of modern free flowing cats and leave the mufflers off.

[bastard]

I had a local muffler shop install duals and I have a single hump crossmember. The guy that did it was an old timer that was well known as the best muffler man in town. He said it isn't the best way to go, but was the best way to do it with a single hump crossmember.
The left side uses the stock Y pipe tubing, but it is cut off before the merge. Both pipes fit through the single hump. The left side then angles back over to the left to its own muffler. The whole thing cost me $140, including a pair of cheap turbo mufflers. We don't have emissions testing here, so no cats.

[77 Canamman]

I would leave the cats off..they build up a lot of heat.

[BR57]

Ditto to 77Canamman, less heat, less backpressure = more ponies.

[Fake Goat]

Just curious, could you do a 2.25" Y-pipe routed to a 3" pipe to get past the "single" hump, then split it back out to 2.25 pipes into dual mufflers? I have a dual hump cross member with an X pipe, seems like this would be a similar arrangement.

Don't know how hard it would be to fabricate, probably cheaper to find a double hump.