No matter what anyone tells you, please understand that no matter how brilliant the product, the difference in such a small engine will be minimal.
Take the biggest number u can imagine but if u multiply it by 1, u don't get a bigger number
For plugs, here's a quick summary:
Platinum for economy and life,
Iridium for performance and life,
Copper for economy and performance.
Copper plugs have the best possible results but they have short lives, which is why the world moved to iridiums and platinums.
Its like synthetic vs mineral oil in our environment. Quick changes of mineral oil will serve u better than longer changes of synthetic oil.
Likewise, if u can, regularly replacing copper plugs is the best thing u can do.
The ik20s have much more life than copper, but they still have less life when compared to competing iridiums. This is because ik20s have sacrificed life for performance, so they are very good plugs performance wise and last longer than copper. However, they still can't match the performance of copper.
So it all boils down to your comfort level and convenience: what do u prefer? Quick intervals and top notch performance, or delayed intervals and SLGHTLY lesser performance?
Your answer to the above questions will decide the plugs for you.
Sent from my GT-I9500