Just did it this past weekend. Use compress air to blow out dirt or anything else around the plugs BEFORE removing it. You don't want anything falling into the combustion chambers when you put the new plugs back in, especially those of us driving in dusty places.
You said you replaced the stock with denso iridium plugs. Are those iridium plugs twin ground electrode plugs? If so what is the part number? The manual specifically says to use only twin ground electrode plugs and I didn't know that denso has iridium plugs with twin electrodes.
I used the Denso Iridium IK16(.4mm tip). The OEM plug I took out is Denso SK16R-P11 (also section 6-2 of the owners manual). Got mine for $8.5/each PM me for info, don't have it on me now. So far, it's working well. Feels like there is a little more power, but could just all be in my head . Also did clean out the OE air filter the quick way by taping the dirty side of the filter. Lotta dirt fell out.
It should work out nicely. I just replaced the plugs (iridium crap) out of my brothers G35x with the Torquemasters. Geez that thing revs!!! He notices quite a bit of difference and picked up a couple of mpg as an added bonus.
Glad most of the G35 guys don't know about the plug...it would be a deadly weapon against the GS.
Originally Posted by Lexizm
Great post I can really use this once I decide which plugs to go with. Anybody try out the Torquemasters in a GS300?