You would get the most benefit from one step colder (ITV22) or two step colder plugs (ITV24) depending on the amount of mods you have.
I recently switched out the stock plugs for some Denso ITV22s as a precautionary measure since Cobb recommends the use of them with their AP. I did not get much KR, even with the stock plugs when I ran the Stage1 93-octane maps.