I used to use Boche 4+ plugs but I moved to the 2+ since they have a smaller center electrode and the plugs take up less room. Also do not index the plugs if it means leaving them loose, thats a great way to slowly mess em up and soul em out. I learnd that the hard way. Its best to have em all tightened in completely. When they were indexed, I heard a loud clicking noise when I suddenly revved the engien from idle on up, it was the last plug cause it was loose. Also indexing em wotn make a difference anyway..
they are located under the plastic cover taht says "KIA DOHC 16V" just take out the 6 screws and there ya go, you will see 2 boxes and 2 wires, the 2 boxes are Coil packs, the 2 wires are what you will most likely want to replace, unless CYL 2 or 4 is misfiring then you will need to replace the coil packs.