I have a 292 in a 68 gmc swb that has dual exhaust, separated all the way out. I've read differing opinions on whether there should be an H tube somewhere in the middle. Q1: What advantages / disadvantages are there to an H tube? Q2: If it's needed, how far back from the engine should it be? Q3: Should it be the same size pipe as the exhaust system, smaller, does it matter? By the way, this is a street engine, no racing or hauling. Thanks.

Leave it completely separate.

A cross-over or balance-pipe in a dual exhaust system is designed to provide an outlet for exhaust pulses competing for space in engines that have an odd firing order. The folks at Burns Stainless compare and contrast exhaust system requirements for even vs. odd firing engines nicely.

Which is more important: to get the right answer, or to know how the right answer was developed?

Thanks for the info. Sounds like I don't need to do anything. I like that kind of solution.

Never mind

I like H-pipes in dual exhaust systems for two reasons.

It will attenuate the peak spike pressure from any single exhaust event, effectively reducing average backpressure.

It makes the exhaust noise "mellower".

Put it as far forward as practical. Most are exhaust pipe diameter, but a smaller one will work also.

I've never run one on a six cylinder on a dyno, but on lots of V8 dyno tests I've run we picked up on the avreage of 5hp (245 HP engine) with an H-pipe.

I have a cross-over pipe on my '68 Chevy 292, w/ Clifford headers. Not really an "H", more of a Russian "N", as the collector from 1-2-3 is spaced ahead of the collector of 4-5-6, and the angled pipe is spaced accordingly.
I was told by the mechanic that this trick would increase torque in climbing situations. Never dyno-ed, but seat-of-pants says it works.

I think it's a bigger deal with V8s. Maybe some sound effects. V8s sound like boats without them. Slow boats.

This subject seems to cause confusion for a lot of us.

I've tried Clifford headers with dual turbo mufflers and with no crossover. (that was before H pipes became popular).
Sounded awful! The 194 w/PG sounded a lot like a small plane taking off.

I had a muffler shop make a Y pipe and run through one turbo muffler.
Much better deeper sound.

Now I have a Flowmaster Y collector for my 292 which should help.
The thing with the crossover is that it seems to me that the way the header collectors are staggered one needs to be extended.
This makes the front three cylinders have an extra long collector vs the rear three. But maybe the pipe size should be reduced before the crossover?
Can anyone shed light on this?
Maybe I think too much?
Thanks

We all think too much. The deal is the quality vs the quantity of our thinking. I'm sure some of our regulars will show up soon and take charge of our mis-thinking.

Well, yeah. as mentioned about 3 posts up, I said we used an angled pipe to cut in the driver's side exhaust to the passenger side exhaust.
For the L6 it's an "N" pipe, not an "H" pipe like on V8s.
The angle should match the difference in lead from the 1-2-3 collector to the 4-5-6 collector.
Yes it works. Also cuts down on perceived noise. When coming past a concrete sound barrier wall on some urban freeways, you hear an Inline snarl, not the growl of V8.
Had mine on my truck since the late '80s.