Best exhaust for 318

I have a 1967 318. It has 3" headers on it, but we will be reducing it to 2.5" so it isn't too large. I would like to know what kind of mufflers to get for it. Will have no cats

1) I'd like it to be less agressive/ more mild, but hear it at WOT. (Im getting cutouts, so no need for it to be too loud of a muffler)

2) Deep rumble when idling and able to hear choppiness of camshaft

3) H or X pipe?

Last, if I want the cutouts to imitate open headers (sound and loudness) as well as possible, where should I place them? Right after headers?

-Kameron

Hi Kameron,

Best I could recommend for deciding between H vs X would be to go to youtube and listen to the way both sound on the same engine so you get an idea of how they differ. You don't need to try to find a 318 for the sound comparison, any V8 should give you a good general idea. Just listen to a variety of small blocks AND big blocks with both. My personal preference is the sound of the H pipe, it brings to mind (for me) of an American V8, to me the X pipe makes the car sound a little limp wristed and European.

You may also want to Google HP/Torque comparisons for H vs X pipes. My understanding is that with all other things being equal, H pipes give better torque numbers and X pipes give better HP numbers on the dyno. The numbers are so close though that unless you are counting hundredths of a second it won't matter.

I used to work with a guy who was the western sales manager for flowmaster, and when I asked him about this he explained that H pipes are the way to go. Of course, he coulda been full of **** so email AND call their help lines and see what they have to say. Call TTI, Dougs, and Hooker.

Finally I'm guessing that you're redoing your exhaust to improve scavenging performance. Remember that your entire drive train is a system that all works together from the air cleaner to the exhaust tip location, and from the carb, cam, heads, torque converter, trans, differential gearing, suspension, to tire size.

My personal preference is for function over form, with a slight nod to form when it comes to wheel style. I don't care too much about maybe a few pounds difference on unsprung weight. If my car ends up not sounding as mean when cruising, so what? I prefer solid performance over bling. If I wanted bling and flash and trash, I'd drive a Ford or Chevy.

If cutouts are are a for sure thing, then why not go to a single exhaust? Half the weight,half the cost, half the noise.

I would put 18 to 24 inches of pipe straight back off the headers, and into the cutouts and then some turnouts. Then I'd go back in front of the cutouts somewhere and y the two sides together and run the single down the passenger side, into a quiet muffler, and out the back.Or maybe dump it in front of the rear wheel.
Nice quiet V8 rumble out the back, quiet comfortable cruising, in-your-face-let's-go, when the cut-outs pop open.Shazzam

2.25 dual exhaust is plenty for a stock/mild 318 IMO.Any more than that and you could lose low end torque.I prefer an x pipe but an H pipe is better than no crossover.I would place either as close to the collectors as possible.
Consider the Dynomax super turbo for mild cruising.

74 dart sport said:

I have a 1967 318. It has 3" headers on it, but we will be reducing it to 2.5" so it isn't too large. I would like to know what kind of mufflers to get for it. Will have no cats

1) I'd like it to be less agressive/ more mild, but hear it at WOT. (Im getting cutouts, so no need for it to be too loud of a muffler)

Click to expand...

I have a 74 Dart sport with the 318. I went with the kit from Jegs and the welded turbo mufflers.

[ame="https://www.youtube.com/watch?v=rlNLaJaZzGQ"]100 3366 - YouTube[/ame]