Using a homemade jig (plans I found here) I made endless loop strings of 8, 10, 14 of 452x, and I shot this against my standard 16 strand D97 on my Palmer recurve. The 8 strand looks like a piece of dental floss, it’s basically equivalent to a 5 strand D97 (452x breaking strength 75#, D97 125#). All strings had rubber cat whiskers and yarn padding on the ends for silencing, and short halo serving so they all were equal.
Shooting thru my chronograph it appears that at most the gain is 2-3 fps with the skinny strings, but that’s within my normal variation when shooting fingers w/o a draw check. Certianly not the 5+ fps gains that others have reported. I would have been able to measure that.
There was no real difference in noise level either, however the frequency was higher and the sound was sharper with the thinner strings. Makes sense if you think of how a guitar works. As expected this was most pronounced with lighter arrows. To me this sound would be very alarming to game. Therefore the advantage was to the thicker string.
I really wanted to believe that skinny would have a performance advantage as it sounds good in theory, so I didn’t initially believe in the results. I ended up testing on 3 separate occasions over a 2 week period all with the same results. I think I get better arrow flight with the thicker strings too but that hasn’t been tested conclusively.
I'm not sure if a skinny D97 (8125) would be better, but I have to think the results would be the same. The nice part about 452x is it's very stable. I have not had to twist the string after the break in. I used a 2 color string, so it's all one continuos loop. Despite my bow's reputation for being noisy, more than one person has commented on how quiet it is with the 16 strand 452x string that I have on it now.