I finally got my 3" exhaust welded up with turndowns before the axle. Too loud for me and I am contemplating running 2 1/2" tailpipes as space is limited on my 67 Coronet; not much room between the springs and gas tanks on this year of B bodies. Anyone running this combo? My motor is a 512 for the street mostly. Thanks

By the time the exhaust gases get to tail pipes, they've cooled and condensed enough that the reduction in pipe size is harmless. In fact, it could arguably improve scavenging since velocity will be higher through the smaller pipes.

Should also quiet it down a bit.

Thanks a bunch; that's what I wanted to hear and it will make matters a little easier on the installation....

Couple of years ago, a friend of mine used to have a pretty wild 66 Satellite with a cross-rammed Hemi. He had 3.5" exhaust with little single chamber Flowmasters and turn downs. But sometimes he would run tailpipes. They were also 3.5" and went over the axle and dumped right behind the tires. Sort of like a old Chevy Nova. It was still pretty loud.

why not just get different mufflers????

whoops sorry yeah any 1/2 system is going to be loud. just get some tail pipes. Don't understnad how people can have a street car with no tail pipes..super annnnoooying

I have a 67 coronet with 3" headpipes and TTI 2.5" tailpipes. Works good and fits easy.

I agree you should have a full exhaust in a street car. With c-boies there is room for only one pipe past the gas tank, so the cure is run the pipes under the frame rails. Real common and looks right. So you could use the 3" if you want. I beleive that the smaller pipes would help as mentioned above. Not sure of application but big pipes are not needed unless you are pushing seriuos Horse Power at high R.P.M.s. Just one old guys opinion.

Here are a few pics of the custom exhaust on my '80 Diplomat coupe project car. This is a 3" pipe, all the way, going through some Hooker MaxFlow mufflers:

I've the same set up as Jeff 383 in my 67 GTX. 3" from headers to mufflers; 2.5" from mufflers to back bumpers. Fit nicely w/ no clearance issues by gas tank or rear springs.

did the exact same thing on My old coronet and My recent satellite...2 inch hooker headers into 3 inch pipes w/flowmasters and reduced to 2 1/2 just before the rear axel...took alot of low rpm hum out..sounds great..many have complimented "that is how all mopars should sound"...

Sounds great guys; I have a set of 2 1/2" tailpipes on the way, should have them installed by next week. Again thanks for your input; I am tired of the low speed humming and resonance with the way I have it now.

just my recent experience with exhaust...

my 5.2L dakota has a single exhaust pipe going back due to the gas tank hanging inside the frame rails, infront of the axle. I used a 3" system, 2 of the long 3" powerstick mufflers welded together. 60" total length, turn down/dump right before the rear axle. sounded great especially at WOT. I'd say it made the truck sound like a 12 second truck since it's got a nice cam to it.

but, on long trips, it was driving me nuts. I actually broke down and put ear plugs in because the resonance was so loud and droning inside the cab.

but...I like the clean look of no tail pipes hanging out.

I had a little more room under there, so I welded a 12" x 3" single chamber glass pack muffler on it, and then took the exhaust up and over the axle, where it now points down and to the rear next to the spare tire, slightly out to the side, away from it.

at idle, it sounds about the same, and it's still pretty loud at WOT with that "high hp crackle" I was looking for...although it is quieter at WOT now.

but, the biggest gain to me was at part throttle cruise. now it's MUCH quieter at cruise, no more drone or resonance. I will now have no qualms about putting my 5 year old in it for a 6 hour trip to Carlisle in several weeks.

maybe instead of stepping down to a 2.5" you can keep it a 3" and add another small glass pack muffler/resonator to the end of it, and still have it dump under the car somewhere for the clean "no-tail pipe" look