I haven't got mine swapped yet, maybe tomorrow. It's supposed to be close to 50 degrees tomorrow.
Anyway, Jay sent me the XP103 plugs, which are 1 step colder than stock, since I'm blown.
First observations: They do not come pre-gapped like most iridium plugs, and the box specifically states that they should be gapped to the specs for the application. When gapping them, it is really easy to measure the gap. The positive electrode is about the same as any plug, but the negative electrode has a little platinum nipple on it facing the positive electrode. Standard electrodes can be hard to measure if the negative electrode isn't perfectly perpendicular to the positive electrode. The little tip on the negative electrode should provide better control of where the spark actually occurs since it provides some focusing. There also should be less shrouding of the flame kernel due to the shape of the negative electrode, it is beveled at the tip instead of flat across the surface. One negative I noticed, maybe not that important but most high end plugs these days come with a protective sleeve slipped over the threads to prevent damage to the tip of the plug. I believe NGK uses cardboard while NipponDenso uses plastic. These plugs were just put in the box.
I'll see how they work this weekend, sorry but I don't have access to a dyno so it will be SOTP testing.
