when to change plug heat range

[TSIfreek]

At what point have you guys swithed over to NGK7s ?? I just put in the Iridiums (6) on a stock motor running stock boost. If I have upgraded fuel system with stock injectors at what boost point do I need to switch to a colder plug?

 

[doug]

From what I've read, many people say anything 16PSI or above and you should probably run 7s. I actually just put some old Iridium 6s back in earlier this afternoon (I had switched to some BPR7ES ones just to see if there was any difference and couldn't detect any) and I'm running 16PSI on a Big16G. I really like the Iridiums myself (even though that wasn't your question)-- they make the car idle more smoothly, so I'm going to look into getting some Iridium 7s even though they're pricey.