I can't say a muffler that works well in a 212 system will work the same in a 2in1. The sound waves when they reach the end of the pipe do a 180. Ability to diffuse, length of pipe, cam timing etc. are all key to sound waves not making it back to the intake port and combustion chamber. This is reversion. There's a lot more to making an exhaust system that performs well.
Despite what m8 owners think, back pressure is NEVER a good thing either. Not sure where this myth even started.
You can hear these exhaust waves actually smacking a closed exhaust valve. If it's open and these sound waves make it back into the combustion chamber it can push the incoming charge backwards too.

https://help.summitracing.com/app/an...aust-reversion

 

The ideal muffler is no muffler. All baffles are a compromise.

 

You're right. They do, in effect, change the length of pipe too. So when using them it's not just a case of using the one that sounds best either.
Khromewerks has a patented Anti Reversion baffle (dogballs) that's been around for decades. It's the same baffle they use in their 3" HP+ muffler. They've been used in straight pipes since the IH days.
Thrashin' Exhaust (Feuling) uses them now. They eliminate or greatly reduce reversion restoring low end torque while not impeding flow and upper rpm power.

https://www.thrashinsupply.com/produ...system-softail



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Depends on the type of racing

 

Who says true duals suck at low rpm torque? Not when they're done right. Too bad these are so butt ugly. How they designed their 2in1 might give you some ideas tho.
Ptetty cool video tho. They sound kick *** and perform.

 

No it doesn't. Some types of racing require mufflers, that's why they're used. The IDEAL muffler is no muffler. That doesn't mean removing your muffler and leaving everything else the same will necessarily make you more power, either. But the optimal exhaust system for anything is one without a muffler. There are no zero-restriction mufflers, just low restriction and higher restriction designs.

 

I was going say this. They use mufflers because they're required to. That changes everything and it becomes a case of compromise.
No restriction, i.e. NO back pressure, is the best. Always has been. Always will be.
My 05 sporty build had drag pipes at first. But they used the hidden crossover pipe and had the same AR baffles (dogballs) in the end of the pipes. I've never seen drag pipes like them that used the hidden crossover. They worked amazingly well but I changed them and put the khromewerks mufflers on with the same AR baffles. This opened up the end of the pipes and had less back pressure than the straight pipes with the same baffles.
This puny little 1250cc build with hammer cams that had 52° overlap did 90/90 hp/torque and over 80ft.!bs. torque at 2200rpm.

The trick is to increase low end torque WITHOUT causing restriction/back pressure that kills upper rpm power but by increasing velocity. This is where using wide open stepped pipes come in. It's what Bassani did with the Pro Streets. The 2 1/2 muffler at the end is as open as open can be. The front pipe is also 44" long. The rear is shorter but with the bend is almost equivalent.
3 steps with the muffler body.

 

You both make valid points, but I can tell you that a SOHC Honda 750 with open exhaust ports ( zero exhaust system / zero "back pressure") will not rev past 6000 rpm

 

The reverse cone megaphones are used to enhance use of sonic tuning (sound waves) and eliminating pressure spikes and reversion.

 

I want to see the Data and proof that a stock de-catted head pipe is one of the best to used....I've never seen or experienced data to back that statement up.
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