This is the stock pipe that got damaged in that dyno clutch explosion.
As you can see there is a perforated material inside that is spot welded along the seam. The stock pipe also has three divets on the outside of it on each side of the pipe. These divets are actually stand offs for the perforated metal. You need these stand offs because it appears that there is also sound deadening material behind that perforated metal. My money says it's asbestos but not sure.
CO

Some more pics and info.
CO

Looks good. Did I miss it, did you gut the pipe or just repair?

I took all the guts out.
CO

That will increase your flow significantly I bet.

be sure to check you jetting, the pipe not should work more like it should

Ok now you need a stock pipe and dyno that. Then dyno this pipe. Wonder what the difference will be

Don't got a stock pipe in my parts supply anymore.
However I will be putting the other two machines on the dyno but I am waiting for a mini tach. Apparently it's suppose to be here the first week in march. Well we'll see. My other order got cancelled so I am not optimistic. Without it I can't do any dyno runs ---- period.
All three machines have a slightly different configuration. I'm interested in the results as well.
Also will have to figure out how to make up the sheet because of the two ratios involved (gearbox ratio as well as clutching ratio). I need data first though.
CO

princess auto doesnt have any cheap tachs that will work, what about amazon

Princess auto only has those laser tachs and I already have one of those to read the axel rpm. It won't work for the Engine because I need all of the data recorders next to each other so that I can film it on my phone. Therefore I need a wired tach.

Amazon -- yeah that's where this crap is ordered from but it comes from China almost always. We don't make anything in north america unless the company can make a gazillion dollars for one item and pay the working man peanuts. Based on statscan data I am making 8/hr less than I made in 1982 based on inflation .
Go to the statscan website and check your pay. You might be shocked.
CO

I know it sounds counter intuitive, but there are scenarios where a textured finish on a surface actually improves air flow. However, I think this situation is as you suspected, the perforated material is probably just for sound.

In the spirit of your inner mad scientist, if you had 2 pipes, could you do some kind of rudimentary flow test? I imagine a 55 gallon drum emptied through your tune pipe..lol

You now have a cheater pipe, I did the same thing on my Pilot back in the day when racing the "Stock" class, used it for the Modified class too.

Check your jetting