I've never heard a stock exhaust with Mike's tips so I can't comment on that...I have the stock tips.
The Y pipe with stock pipe and tips sounded PERFECT to me.
True straight-through duals ARE louder. And raspier. Not bad...but it IS a bit louder. As the system built up some carbon the rasp went away. It is still reasonably tame and unobjectionable when you drive it easy. I would imagine straight true duals would be TOO loud with Mike's tips if they megaphone the way you describe. Unless you like it really loud...which I do.
Keep in mind that even with straight duals the interior drone is STILL miniscule. Sure, you can HEAR the exhaust, but it's from the BACK of the truck. it's not like a Flowmaster where it feels and sounds like you're sitting on a giant industrial transformer humming and vibrating.
I don't think I have any pics of my install...I can look.
Regarding the H pipe or X pipe, H pipes are historically "deeper" sounding and better for low-end torque whereas X pipes are higher pitched and scavenge better at high RPMs making more horsepower. However, I use my truck to pull a travel trailer and I have no use for high end horsepower. I went with true duals to get more low-end pulling power and boy did it ever make a difference.
But...the idea that the H pipe (or X pipe) makes a difference on our trucks is a crapshoot. As Mike in Az pointed out, since you can't put the the H pipe or X pipe equidistant from each side of the engine there may not be any benefit (and it might be detrimental). It is impossible to predetermine what part of the powerband you will be affecting. Again, it's a crapshoot.
However, I have a giant collection of Trailer Life magazines from the 60's through the 90's. Back in the 60's and 70's when everyone was trying everything they could to get power to pull giant trailers with family cars, these magazines contained literally dozens upon dozens of old-school tech articles about the massive benefit of dual exhaust for trailer pulling...and ALL of the articles discuss installing an H pipe as close to the engine as possible. And, on a good number of the cars, the exhaust pipes from the manifolds to where they installed H pipes were NOT at ALL equal. Their actual rationale was to install an H pipe BECAUSE the pipes weren't equal and that the H pipe equalizes the system. This however is the opposite of the rationale Mike gives for NOT using an H pipe.
Yet, all the testing reported in those 20 years worth of Trailer Life magazines in the 60's and 70's ALWAYS netted gains from installing true duals with an H pipe. It must be noted, however, that they ALWAYS installed the H pipes...so there aren't any comparisons between say a 1971 455 Buick with true duals vs the same but with an H pipe. And, alot has advanced since then...but you've got to remember that these were true old-school mechanics who really did know their stuff back in the day.
I CAN say that on my truck it made a HUGE difference going to true wide-open duals. I don't know if the H pipe hurt or helped. It SOUNDS great, but the off-the-line pulling power is unreal. I was expecting a minimal change (I did the duals on a whim) but it's almost as much of a gain as when I went to 4.56 gears from stock. I have the stock cats and stock piping, with the only mods being a ported and polished throttle body, no MAF screen, a 10 year old K&N filter, and a modest tune from PCMforLess.
But no, getting to the point...I doubt the H pipe is really required. After talking with Mike, he said, "You won't know until you try it and see" so I did. But he's probably right (as usual)...besides from a deepening of the sound (and equalizing the tone from the back of the truck) it probably doesn't provide much benefit. But then again, to reiterate, those old articles stated to install an H pipe specifically TO equalize an unequal length system whereas again Mike has stated that if the pipes are unequal to begin with then it's pointless.
Regardless, I wouldn't do an X pipe...even with the H pipe the sound was a bit higher pitched then I expected at first (remember, X pipes are even higher pitched). I would keep in mind at all times though...with the megaphone tips, it's going to be REALLY loud.
I think it's worth true muffler-less duals for the performance gain. They REALLY sound great and scare little children, rodents, pets, motorists, and car alarms into a frenzy when you step on it but amazingly they are quiet enough that I can pull into a campground at 1am and not bother anyone.
In all honesty, I thought the Y pipe with stock tips was the PERFECT sounding exhaust regarding volume, tone, and control. Summarily, true wide-open duals with stock tips and an H pipe sounds like the Y pipe on mild steroids. It borders on "OK this is the absolute limit of how loud and obnoxious I want to go" but it doesn't cross that line. And, it's quiet if you drive it easy.
But man...when I'm passing slow moving trucks and RVs, screaming up mountain passes in 3rd gear the sound of that loud-ass exhaust beaming off the front of my Airstream with the top down puts a HUGE smile on my face whilst at the same time it expounds a look of profound pure horror from those faces of whom I am deriving the utmost pleasure by leaving them in my dust...pulling a 5000lb trailer!!!
Good times.
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