I have a GMC Yukon Denali with the 6.0. I am looking to do plugs and I was wondering what people have heard about the NGK Laser Iridium vs. the NGK Laser Platnium. The Iridium plugs are more costly and sound pretty top of the line. Anyone know much about the two?

Also.....I just bought the Super Chip programmer for the truck and programmed it to the 87 Octane setting. Made a HUGE difference and I got 1-2 mpg more out of the engine. Tranny doesn't shift as much going up hills, seem to be using less throttle to get speed and maintain one and smoothed out the engine too. Not a bad purchase.

most of the ac delco plugs that come in the new vehicle are iridium, but I dont think you will notice any diffrence between the 2.

Just get some ngk tr5's, gap them to .40 and you'll be good. NGK makes the delcos, you can buy the iridiums if you want but they aren't really worth it on these engines. Here are the NGK part #'s NAPA should have them in stock
V-Power - 2238
G-Power - 3186
Laser Platinum - 3784
OE Laser Platinum - 6044
Iridium IX - 7397
I'd get the iridiums if you aren't gonna add any nitrous or forced induction, I bought the TR6s for the planned procharger.