the stock srt6 plugs are the laser iridiums (ifr6d10), i recommend these plugs for the kompressor motors, not the na motors.
i personally changed mine at 22k miles when i swapped in the new cylinder heads but that is just me. i would have otherwise left them in there till 50k miles unless an issue arrised.

as for the gapping tool, i get those for you guys so that you dont break the tips on the expensive plugs with a $2 gapping tool mentioned above that opens the gap by wedging force, please watch the ngk video on the plugs page on our website showing why this is important. the plugs are only availabe in packs of 4, if you break the tip of 1 plug you just cost yourself enough to spoil your mood for sure.

the wire removing tool on ebay linked above... works great and is correct, it is a 17mm wrench with a funky bend to it so you can pop them off by leveraging off the valve covers. if you just pull the wires out by hand you have a very good chance of damaging the stock wires. i purchased mine from ElPaso tool on ebay, he has a lot of benz tools and has been reliable thus far.

the wires we carry are 8.5mm thick, they are a nicer wire than the factory wire and actually end up cheaper than oem wires too. that combo is on both our srt6 and c32 at a 0.039" gap

if you srt6 has under 50k miles and is running/idling smoothly then i wouldnt touch the plugs/wires yet.