Since there is basically no videos of these except the ones recorded with a calculator on tanabe's site, this is the best one I've found so far:

 

perfect sound...

 

Bought and installed this. Great sound, decent note at idle but retains that slightly muffled note all the way to redline, doesnt open up and get raspy. It necks down very slightly at the cat flange from 80mm to what looks like dead on 3", looking through the central resonator it seems the muffler has what almost looks to be a floating sleeve/cylinder slightly smaller than the 80mm piping but the central bore is still large from the looks of it ~3", and at the rear muffler it necks to about 2.65" according to some measurements I found on here (the gas is much cooler by then so its the best place for a reduction in ID). Still flows very well, better than what I have before without being loud which is exactly what I wanted.

Some results on E85 with conservative boost/timing:

 

Those numbers are not accurate, you can see the torque curve going back up at the end inflating your results.

 

The red run sure a touch, the blue line doesn't. You'd be talking a couple hp anyway.

 

Probably more around 15-20

 

I like the tip style on their exhausts.

 

As I said the blue run does not go back up. They were 2 different stretches of road that both looked pretty flat and log well for the most part and the red line doesn't go back up as such, its got a notch out of it you can see it in the power curve too. It was a uneven part in the road if I start the run too late on that stretch I'll hit it. I agree with the red run being flawed, I just left it in to show ballpark and didnt think it'd be much down on the other run. Remember too I'm not running a 30psi boost spike US style, so the torque will not fall away anywhere near as much. I appreciate your input, but I'm just showing the exhaust flows well over 400HP which is does with ease.