LS4 Performance - LS4 Spark plugs

Which one of these NGK'S are best for the GXP? And should you leave the stock gap? I have the following mods in my signature. Thanks!

V-Power TR55 .044
G-Power TR55GP .044
OE Laser Iridium .044
Iridium IX TR55IX .044

I have the NGK V-Power TR-55 plugs gapped at .055 an the car idles way smoother than stock and has no spark knock/detonation problems. Tried a .050 and the car seemed sluggish with a stock tune. This is the 3rd vehicle I have run these plugs in with zero problems, trucks plugs were still good at 30k.

How long would the Iridiium IX plugs last?

Is the gap set from NGK or did you modify the gap because of MODS?

It was a common gap to use on the ls1 to get rid of slight spark knock on a stock ls1. Ive used these in my z71 the same way. The out of box gap varies on them so I have had to set them each time. Even on my 96 Saturn SC2 NGK's seem to be most used plug. Irridium and Platium plugs are for longevity, not necessarily the best performance, you have irridium plugs stock, so if thats what you want I would just check the gaps on the stock ones (mine were not all the same gap from the factory), and leave them in.

I have the NGK V-Power TR-55 plugs gapped at .055 an the car idles way smoother than stock and has no spark knock/detonation problems. Tried a .050 and the car seemed sluggish with a stock tune. This is the 3rd vehicle I have run these plugs in with zero problems, trucks plugs were still good at 30k.


I have NGK V POWER TR .055 PLUGS GAPPED AT .59