my merc,which is a 1987,has the origional champions in it.put new champs in it,ran like crap.put the old ones back in,runs purfect again.dont know the reason why,but it does....
my evinrude has champs in it,put champs back in it,i only paid $2 a piece for them.my local autozone,pep boys,and advanced auto didnt have anything in stock for them,they had another plug they cross my # over to.but didint have enough to do my 90.
as for all plugs being equal,im not 100% sure on that,but my ford runs better using motorcraft plugs/autolite plugs in it.as my crysler runs champions in it,my buick gets ac/delco plugs in it.i have aluays stuck with the plugs it came with,and never had a problem with it.guess you could say stubborn..
i have heard many people rave about the splitfire plugs,but heard many people say they are trash,no gain in hp,or mileage.but people still put them in,saying there getting the gains.but are they really?or is it in there heads they think they are getting it.
if you want to put the $22 plugs in,be my guest,im not going to say they are trash,maybe your motor calls for them,maybe they dont.but to each his own....
i read somewhere that they put in what the manual says to do,not to jepordize there 10,000+ motors,i agree with that 100%.what mine come with,goes back in all the time.if yours calls for ngk's,put them back in,champions,put them in.but what i dont believe in is the plug manufactures have a thing is we got it,you want it,you PAY dearly.they manufacture the plug per spec for the motor manufacturer,peroid.just a tweak here and there,nothing crosses to it.
as i say to each is own,if you want to put an aftermarket plug in,to save some $$$,hey its your motor,not mine,if you feel confident on doing it,more power to you...