Exhaust dyno sheet, and some questions to ponder

[SCSi]

I was browsing around the InterWebs, looking to see if I could stumble across any new parts that were coming out for the Si when I came across this dyno done by SuperStreet for the Magnaflow exhaust. I apologize if this was a repost, I did some searching beforehand just to make sure.



The funny thing is that in the article, it says that the Magnaflow exhaust is a 2.5in, when I thought that it was a 2.25 like the stocker. Even the picture makes it seem like the two exhausts are very similar in diameter.



So I have a conclusion, and a couple of questions.

1. Is the magnaflow exhaust 2.5 like the article says?
If so, this dyno sheet could provide a guideline for those looking into 2.5in/60mm exhaust as to whp and tq gains (6.5 and 7 respectively with midrange gains of 9 and 8)

2. If it is not, then the hp gains could be coming from a less restrictive muffler, which also makes the 8whp claim of the Mugen Axleback more believable. It also makes the potential gains of larger exhausts more credible (10hp for Vibrant, 13.5hp for LSD, 1000+hp(jk) for the Skunk2,70mm).

I have noticed a dearth of dyno sheets just for exhausts, so I simply thought that this was an interesting issue to investigate.

One other thing that I noticed is that the baseline is right along the usual hp for a stock Si, and that upon further investigation, the second dyno was 6 degrees hotter than the baseline, although with slightly less humid air. I don't know how to interpret the humidity part.

Anyways, anyone have any thoughts?