Stock replacement would actually be a TR5IX I think. 5 is the right heat range for stock and the TR. IX is the iridium I believe.

 

I haven't added the boost to the denali yet so I can't say, but when I had the lightning I went thru a number of brands, and most recommended the NGK TR6's, but I tried out the denso's and they were the smoothest running plugs I ever put in it, these that I am going to link are the TR6 heat range

Denso 5326 Denso Iridium Power Spark Plugs

 

Just so you know Iridium tip plugs tend to hold heat more then a copper core and can be more prone to detonation.

 

I don't know one way or the other, but I do know high boosted vehicles choose iridium, alot of the 1000hp plus supras I know swear by them

 

https://ls1tech.com/forums/forced-in...ix-tr7-ix.html

Kateck chose them for there 800hp ZR1
http://forums.corvetteforum.com/c6-c...-delivery.html

 

Ok, whatever you choose is up to you.

 

I run an LS9 plug. Clearly it's working for GM.

 

Considering the lack of timing it makes they shouldn't have a issue.

 

im also running a factory delco ls9 plug, ac 41-104 i think is the part number. from what i researched I believe they are either a 6 or 7 heat range plug and they are iridiums. i think it was Janetty that was using them in all of his high hp boosted applications from camaros to vettes and whatever else and swore by them over NGK plugs and since i work for an auto parts store i figured id try them out since i could get them much cheaper than retail. cant say that ive had any problems from them, truck runs good, no detonation so far. ive got a set of br7ef's in my console gapped at about .030 that ive been debating putting in the truck but i just keep putting it off.

 

It's not the ground strap's temperature that changes, it is the tip of the center insulator. Here is a good read:


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