I'm sure that there's room to optimize the X configuration once you've settled on using it. Dr. Gas has simply been at it longer than most.

Anything that looks like an X and connects the flows between the two banks acts to balance the pulses and the flows, assuming that the lengths of piping from the manifolds or collectors to the X and the downstream restrictions are about equal side to side. Some likely a little better than others, but at that point you're looking at a fraction of a percent difference in terms of power. What the teams in the top NASCAR series would jump on without second thought would barely show up at the dragstrip and you'd never notice it on your street driver.


Norm

 

Just to add to this.. My fathers AMC originally had straight through exhaust. Due to the size of the car are the absolutely huge trunk it had an aweful drone anywhere above 30. After a few years of my bugging him I sent him a generic H-pipe kit from Summit. Once installed it made a huge difference is doing away with most of the drone, smoothed out the cars sound both idle and wot and gave a slightly noticeable low end performance boost. Just felt like it had a bit more with an initial shot of gas.

Its still got a nice rumble but it certainly smoothed out the sound of the car a lot. If an X smooths it out more I don't think I'd like it myself.

 

I have the hedmanns with the H and flowmasters and really like the sound. If I were to do it over I might choose a different muffler, but for the price etc.. I think the setup works and sounds great.

 

The Dr. Gas unit isn't like everyone else's x pipe though. It's not an actual x junction, it's more like 2 90* bends that have been siamesed together. The opening between the 2 sides is an oval shape that doesn't use the whole side of the pipes. It even has a proper flow direction, so there is a front and it needs to be installed properly.

Yeah, they've been doing it a lot longer than most, but they also put a lot more thought into their designs than others do.

 

i personally wont use flowmasters again, ive used a few borla setups which were awesome but really expensive. I think magnaflows the best happy medium out there.

Ive never used an h pipe setup though, interesting points on each merge type..

 

My vote goes for an H pipe with straight through mufflers. The H sounds better than the X in my opinion. Whatever you do, do not go with dronemasters. They are annoying inside the car.

I like Dynomax, Magnaflow, or glasspacks.

 

That's exactly the way I'd start if I was to fab my own.


Assuming that you don't try to make the two pipes fully overlap in the merge section (and end up with a perfectly round pipe there), an oval shaped opening is what you will end up with. The amount of cross section "overlap" will determine the exact dimensions of the oval. More overlap probably makes for better welding access into the crotches. I'd expect minimal overlap (and the smallest possible resulting hole) to preserve at least a little of the traditional V8 rumble.


Any idea what defines this?


Norm

 

After reading all the great input, I think I have decided to go with an H-Pipe so I have called up the shop to order one before I stop in.

My reasons were:
-Most people who like the X pipe get super technical on why it's better. They may all be valid points but my life is around keeping things simple. I think the 65 is a simple car. I think the X would be better on a newer car.
-I don't want a raspy sounding motor at high rpms, I like the deep muscle tone
-I'm working with flowmasters and an X might be worse sounding then the H
-It was my gut to work with the H in the first place
-Youtube vids with the X were probably more on the newer cars and most their drive bys sounded like cans rattling
-The X pipe might give better high end power because exhaust is flowing faster and offers a smoother flow design to escape, but my driving is not for the track
-Since most I care about is having an even pressured engine and good sound, for what my car is and for what it's not, the H seams to fit better in my category.
-I might have better success later installing a driveshaft loop with an H installed vs the space an X takes up.

I hope all my reasons end up not causing any regrets later once it's installed, we'll find out!

 

The latest development, the "O" pipe, is radical and takes things further than the "H" and "X" pipes. Exhaust gases never ebb and flow, never poison the environment and never enter the car.

 

I had to call Dr. Gas to find out direction. The x unit itself has a wider portion to the pipe layout on one end than the other, which is the entry side. They also have a plate welded on it that says "Dr. Gas X-scream" etc. And if you lay it down so that the words are right side up like in a book, the top is the front of the car.

As far as x vs h, it seems like you got all of your reasoning backwards. A properly designed x performs better than an h at all rpms, regardless of the technical reasons. And an x tends to make for a much smoother more mellow rumble and a smoother note at mid-high rpm than an h. The h will be more raspy. The simple fact is that a properly designed x promotes better bank to bank balance in the exhaust system, which is a major problem for all 90* V8 engines. Ferraris and F1 cars sound like they do because they use a 180* crankshaft and have no need for a balance pipe of any sort between each exhaust bank. Some x's are just an x junction that do little to nothing to balance the exhaust, whereas the Dr. Gas unit is actually designed intentionally to balance each side of the exhaust.

When I put the Dr. Gas x on my car using the same mufflers, the note at idle was a deeper rumble and it was a lot smoother and less raspy than it was with the h I had. And the tone of the exhaust in general is much smoother, though somewhat higher pitched.

http://www.youtube.com/watch?v=WoDh1S57qtU There's a vid of a Dr. Gas setup on a Fox, using their mufflers. Keep in mind the muffler will also effect how raspy the exhaust is. Flowmasters for example are typically quite raspy.