Iridium IX series BKR6EIX-11 (advance auto part # 3764) or laser iridium IFR6E11(#6741) These are for a b18c1 and d16y8. When I use to run nitrous I used the gsr plugs in copper for single cams or ls motors and you can also get them in a 7 (fits ITR)which for you would be two steps colder for your application.