Re: what plug is best to replace stock
i've never been a fan of Splitfire plugs. when they first came out years ago some guys i used to buy honda parts from did a review of them for a major magazine.
they put them into a mustang 5.0 engine on the dyno, and within a few minutes one of the electrodes broke off and destroyed the engine.
as far as a 3 point plug on our engines, i think it's overkill. there's only so much (or so little) performance gain you can get on a single cylinder engine. i mean, every little bit helps, but the difference between a good NGK BH series plug and some fancy exotic plug is so minimal it's just not worth the price difference.
that being said, i think any name brand, quality plug is miles better than the stock one. the quality is so bad i just throw them into a box and forget about them. some people like 'em, though. if nothing else, i'd change them out just for peace of mind.
all my bikes run a 7mm copper core wire, NGK B6 or B7HS, and a nice tight boot, gapped at .030
can't go wrong with that.