I pulled my plugs and had a look at them since I am stepping down on boost a bit. They were a bit black, indicating they were a little too cold.

I had used 1 step colder denso U-groove plugs which are recommended for the 18 psi boost range.

But, since I have been using water/meth injection, I suspect that has been cooling the IATs well enough. I suspect, but don't really know. I do know the plugs are blacker than ideal.

Soooooo, I've swapped back to NGK iridium stock units.

If going up on boost without water injection I would say use 1 step colder, but not with. Just my 2 cents.

 

Here is a photo.

These are not horrendously black, but would you agree they look to be a little too cold?

These have about 1000 miles on them.

I'm happy to donate these to anyone who wants them. Obviously I'd ship the set of 8, even though there are only 6 in the photo.

**Update, Plugs have been claimed** no longer available

 

I have another set of plugs to donate which are denso u-groove 2 steps colder. I was planning on using these with 18 psi of boost + NOS, but have since decided I don't want large dents on my hood originating from the inside

So if anyone wants a set of 8 denso Q22PR-U, they are free for the taking