NGK DPR8EA came in it. The shop sold me NGK DPR8Z (4730) as a replacement. Which is correct please.

 

Also what is the correct gap? Also, the plug that was run today is dry and very black. It's cold here, I don't see how it could be running rich. Is that what it means. I just picked up this 400ex today. It's stock. Thanks.

 

DPR8Z is stock, DPR9Z is also recomended and makes it runs a little cooler.