As the title says, what are your preference?

BR9ECM

Ordered the iridium ones, thanks!

Think i read some where Iridium isnt good for 2 strokes? .. just stick with the recommended (as above), there good and they work

Different people say different things. I've been running iridium plugs, and they've been fine. I don't know if there is much to be gained, but I've never fouled them (unlike my four stroke CAR today), and they've lasted well.

I had recently experimented with iridium plugs on my RG, been using them in the car for a while, in fact they are due for a change cause it's been nearly 100,000 miles!

So back to the Gamma, I was having issues with ignition, someone replaced the wires with a resistor type and the ends where they go in to the coils have chard form bad connection. So I replaced the wires with copper core ones and new caps (got a wire set for MG, the only way I could get a non resistor set up) but still bike would flood in the top of the rev range under hard acceleration, sure sign of weak spark. On the advice of a Rick Lance (He is a known Gamma guy in US) I switched to Iridium plugs and the problem went away! The idea is that Iridium plug is easier to fire, less chance of fouling. So bike is all better, but I didn't rest, got new coils and the bike got worse, swapped to old coils and the 2 front cylinders just would not run anymore, bad CDI? I don't think so!

After some 3 hours of swapping and testing I discovered a problem, while I was switching coils the plug cap which is proudly stamped "Made in England OK" fell apart, I must have puled on the wire and resistor inside broke. Lousy way to waste a sunny Saturday chasing electrical gremlins and discover that my "non resistor" wire set came with resistor caps!

So now that ignition is sorted out I'm back to good old conventional NGK since I don't plan on 100,000 mile service intervals on my bike I will use the cheaper more common plug.

"Made in England OK"

A sure warning sign.