I am using 8's in my car, told to use 7's on a cold day.

5's for moving the car around but once warmed slightly I'll chuck the 8's in, have to be careful changing plugs on a hot motor the thread can gall in the head.

A new set of regular NGKs will make your engine run better. So will a new set of Irridium/platinum NGKs.

The advantage of platinum, they will last longer without regapping every year. With the regular $1 plugs you need to check and regap them yearly.

Also they can withstand longer the ultra-high spark voltages of the new ignition systems. Won't make a differnce on the Datsun electronic ignitions, which are only medium high voltages.

NGK South Africa only list 8 for aprilia and 9 for yamaha, both for 125 bikes

NGK Iridium number look like this 'br6eix' number's go from 1 to 11 I think? a 6ish is what ya want. dont know what the denso numbers are (only other brand that dose iridium)

Iridium superseaded platnum because they hav the same benifit but are cheeper to produce, end cost is about the same.

any idea what the part number on the platinum plugs are?

I guess its worth finding out, will post what I find out.

You must remember that I bought my Iridium plugs about 4 years ago & what I paid for them here, back then, may have no connexion with what is being asked in South Africa today, so make an enquirey & you might just get a pleasant surprise.
Also ask about Platinum plugs, they are also less costly I believe.

Yes, I also used BP6ES plugs & they are bloody good value, but I wanted to step up to improved ignition efficiency in one of my hard to start motorcycles.
The NGK Platinums that I used turned a hard starting beast into a first kick pussy.
That's what sold me in the first place & I have been using NGK's premium line ever since.

Aish thats $80 a set= R600 south african. sjoe, bought a set of BP6es for R36 LOL, maybe I'll put it on my christmas list with an E15 elec dizzy!!!

I have no idea what regular plugs cost these days as I haven't bought any for about 25 years but the Iridiums were not cheap at about $20, ..........each.
Platinum is still available in other brands I believe & are probably less costly. [the Iridiums were fresh on the market when I got them]

For me it is worth it for the improved ignition performance & long life.

Really, what is the cost differance between normal platinum and irradium plugs?