The Street Rod has the better intake, a slightly higher compression ratio, a modified cam, and a "low restriction muffler". And an 18% gain in HP and 8% in torque, which is not too shabby at all.
But -- it's also running an EPA-compliant tune which is probably leaner than it should be. And the "low restriction" muffler still sounded much thinner and raspier, to me, than a Nightstick or V&H or other muffler. It still has to be 50-state compliant, so I bet Harley left quite a bit on the table there for the sake of meeting 50-state emissions laws, noise restrictions, and improving fuel economy.
So is it possible that TucsonMax's Street is delivering 2hp more than the Street Rod? Depending on the dyno, sure -- the only way to really know would be to run them both on the same dyno. I have somewhat similar mods to Max's, and my FP3 "dyno" is showing +13.4% peak HP and +8.5% peak torque, putting it pretty close to the same ballpark as the Street Rod, so I think Max's numbers are certainly reasonable. And the Nightstick I'm using is tuned for torque, not HP; if I pulled off the end cap and retuned for a free-flowing exhaust I wouldn't be surprised if the peak HP was up there with Max's and with the Street Rod's.
But that's all comparing modified Streets against a stock Street Rod. I fully expect that if you modify the Street Rod accordingly (i.e, put a truly free-flowing muffler on the Street Rod and have a professional tuner map it for optimum performance), that the Street Rod's advantages (higher compression ratio, bigger intake, and hotter cam) would push it significantly ahead of what we can get from a Street 750.