2003 GS300. I'm changing the plugs and wires soon. What plug is best for this engine. Has anyone found any wires to be better than OEM. Last item, is there anything I should do why I have everything apart other than clean the throttle body? Thanks.

 

Plugs? In all my personal experience with running muscle cars, and a supercharged dragbike, I found the NGK Iridiums to be themost reliable, best running, longest lasting choice for me. IMO...

 

Do NOT use iridium spark plugs. If you look in the manual for your car the 300 requires platinum spark plugs and will not run right if you use iridium. There are lots of threads about which platinum plugs to use

 

Nippon Denso or NGK.

 

The point is arguable- Iridiums are known to last longer, fire cleaner, and are just a tougher plug- hence their popularity in high performance engines. Platinums are very good too, but Iridiums are considered a compatible upgrade. What was specified in a manual 20 years ago is subject to revision.

 

Ummm it clearly says to only use iridium tipped

 

There was a update to iridium during the GS's run. I believe 2001+ got them from factory. And all IS300's got them. That is because iridium is indeed superior and a good idea to put in. So since you have a 2003, if you go with OEM you will be fine. I am a fan of NGK and run the Iridium IX line in my 1998. You will also notice that for some reason the update also included going one heat range colder. I don't know if that is because the engine needed it or that the composition of iridium requires it, but make sure you run a 6 heat range and not 5 as the 98-00 had. The updates were done for a reason and for me, going to a colder range iridium made no ill effects in my old 98 that came with heat range 5 double platinum plugs.