I use and have always used NKG copper plugs. Stocks are BKR5E-11, in engines above 100bhp I tend to use a colder BKR7E-11 available online of through Matt as he usually keeps a good stash of them. FYI, they were just about right in a 125bhp engine.
Be very skeptical of any plugs or leads with claims of horsepower gains, these are just nice stories relating to people who had a sub par setup to begin with.
Iridium, platinum or Gold Paladium just offer potentially increased longevity of the plugs under ideal conditions and do not offer any performance increases as such. It's very easy to shove in a set of worn old plugs, do a power run and then put in a nice fresh set and see a minor change of which could easily be argued to be within the accuracy of the dyno given the conditions at the time.
If you over gap a plug and the electrodes wear then there will be more risk of a misfire as the gaps open up during their lifetime......the only benefit in that sense of a Super 4 is the electrodes perhaps wear slower individually due to the increased number of ignition paths compared to a conventional single tip plug.
Personally I don't recommend over gapping and just because EBB did it, it doesn't make it the best choice to make. Yes, one can do it but since it only increases the potential for something to fail in service, one could argue it perhaps has more in the way of a potential downside than an upside. You car will run very well with the plug gaps set to the manufacturer's gap settings and last a good length of time
