If the TRD
Racing plugs are Denso IK22, all they are is the standard Denso Iridium Power (0.4mm Tip) Plug, one heatrange colder than what is specified by Toyota (IK20/SK20R11). You can buy them without the TRD
branding for about $12/each - probably less.
Colder heatrange plugs help stop pre-ignition, and are generally used in highly tuned normally aspirated and forced induction engines. For an example close to home, the 1ZZ plug heatrange is 16, whereas the 2ZZ heatrange is 20, 1 heatrange colder. For a standard internals road car there is probably not much advantage to go for a colder plug, unless you drive you car in the 7-8000RPM range for extended periods. A downside of cold plugs is that they foul easier then hot plugs.
the trd iridium racing plugs are the best i seen so far. they are made by denso for trd part no.19059-sp004-22 plug type ik22
according to this quote found at this link Spark Plug Info
it would be ok to use the IK20's in a GT, since the have the same TPI, thread length, 5/8" diameter, gap, and electrode diameter. The heat range being the primary difference making them more susceptible to fouling at higher RPM ranges for extended periods ( although I think this is true for any plug but i see the reasoning here) placing the IK20 in a GT would be like placing the IK22 in a GTS. Now to the reason I ask...I have been round and round with Toyota service dept about why my engine keeps idling funny, they said it was my MAF causing the CEL to read out engine misfire. This started april 24th (which they said there was no abnormal sound for the make and model...errrhmmmm BS
)...so i took my mods off, except a K&N OEM filter element been stock since then...still the same prob...month later they told me it was the K&N OEM filter in the stock box messing with the MAF...so i had the injectors cleand, the MAF (they said was clean). All the time i had a gut feeling this was an engine misfire (like they diagnosed when i had them check the CEL code)...so i decide to go their way back 100% stock paper filter yada yada...still the same shit but got worse...engine felt like it was gonna stall every time i decelrated and hesitated horribly when accelerating; idle was shit too. SO the damn CEL kept coming on every time i cleared it...I got pissed, i spent $175 for this shit to still be happening even after i asked them to check the plugs, wires, coils, and take it out for a 100mi drive if they needed too. So i took it to autozone for a free OBDII readout
and low an be hold... P0302 then P0300 then P0302 (in english misfire cyl #2, multiple misfire, misfire cyl #2) so I told the guy what Toyota told me he said NO WAY a MAF would cause that...I agreed, so I bought Iridiums but since I didnt have the stock plugs to compare or internet avaible in the store, I had to go by what they told me...IK20..I saw the screen as he looked the part up...so there were no alternative Iridiums for the GT just plain Cu autolite plugs and platnum plugs...I am going to install these IK20's tomorrow but wanted to check to make sure my engine wont blow up when I start it
I doublt it will but I wanted to consult the gurus of ecelica before I either return them for IK16's or installed what they gave me. Sorry for spelling, grammar and length...and THANKS in advance and again Many Props to ECELICA...