NGK Iridium IX vs. Laser Iridium Spark Plugs

Hi guys, I'm trying to find out the difference between the NGK Iririum IX and NGK Laser Iridium plugs.

NGKs own material: http://www.google.com.au/url?sa=t&rc...58187178,d.dGI

does not really cover it, saying only that the Iridium IX are just that bit better then the Laser Iridium, however can last only about half the mileage....

This site however has a good breakdown, but doesn't say if the IX's give better fuel economy over the Lasers: http://www.jscspeed.com/catalog/NGK_...6-19569-1.html

Does anyone know if there is a noticeable performance / fuel economy benefit to using the IX's over the Lasers?

Or if I should even be using the NGKs in the MPS6?

Thanks.

They won't publicly say what the difference is. They wouldn't want competitors to know.

Either way, they won't give any major improvement in fuel economy. Most of the people who say they did get a big improvement by going from one plug to another type forget the fact that they are usually going from an old worn plug to a brand new one

Plugs on an MPS aren't hard to change, so I don't think its worth really the expence of going to a longer lasting plug unless you do a lot of KM.
If you had a V6 magna or a Toyota tarago, then I'd say get the longest lasting plugs you can find