OEM calls for iridium. Have used NGK for yrs now, recommend often and rarely a problem with them. They go for half price of OEM plugs, but seem to do same mileadge without much deterioration, very good call from GRC, site post gaps specs also.
As a afterthought, don't be fooled by those rapid fire plugs, they suck in a waste spark engine. Some say the NGK iridium don't last, in my experience, they do fine up here for north climate and the gas we use.
For cold starts, you want a really clean pathway. Since I tend to ramble sometimes, plugs are a choice, and there is a plethora of them. Yes, my french brain actually can write that word.
In the cop cars we fix, as Jack wrote, we also go OEM. But there, budget is not really a problem. But up here, we don't get USA prices unless you buy in bulk. So 1 oem plug can go for 10$ times 6. For some ppl. that is a weeks gas money for work and day care or a nice family outing at your local Denny's or other family cook shop that passes a friday night with the kids.
Again, more rambling. But as said before, we still see these era cars in the police force, they are mostly for ticket cars and detective cars. I guess up here, we don't have hollywood budgets for the detectives. But who in their right mind would be a detective in a rookie awd drive interceptor?
I think GM is out of the cop car game, ford also is coming soon among rumors, the awd charger will be the only option with a hemi. Hmm, gas tax anyone?