I guess my point was more that: I don't know whether the hp gain was more from using the irridium plugs than that of using the standard plugs, because I didnt see an obvious failure, and it's not like the bike was running as if it had an obvious spark plug failure.
Either way I am happy
My assumption is that the the gain would be from the plugs being new, and not the type.
Used plugs can easily give the appearance of being OK, yet not make peak power and do so without any obvious indicators.
Fresh conventional plugs should make the same power as any of the noble metal based small centre electrode plugs.
First it was Platinum, then came Palladium, and nowadays Iridium is the big thing.
Iridium is related to Platinum.
Platinum and Palladium are also excellent catalyst materials, in addition to being very corrosion resistant.
Iridium has excellent corrosion resistance, even in extreme temperature environments.
Hence its use in spark plugs for the centre electrode.
It's a great choice if one wants a 100,000 mile plug as part of being able to maintain allowable tailpipe emissions after years of use.