Just curious has anyone used the G power and then switched to the IX or vice versa and if so was there any noticeable changes to performance, mpg, etc...

 

Stick with the Iridium IX. It's simply superior to the G power plug. The NGK website outlines the key features, and the Iridium is just better.

 

NGK platinum and iridium are the correct plug for the TL hi energy coil-on-plug ignition
the irids are stock in gen3 and better than plats - ok for us to run

the `wrong plugs` have too much resistance and dont last very long,,months usually,
and a new thread on `why does my car run bad, I just put new 2buck chuck plugs in it' is started,,again

 

NGK plugs are usually the alternative plugs for most honda models if not all (i even put in NGK iridiums in my moms honda oddesy (not the smae ones that i used in my TL mind you))
But I had the original plugs until now (120,000 Mi) so yea it made quite the difference.
And dont forget to seafoam and clean your EGR port so you clean that crud out using your old plugs and THEN put your nice shiney new ones in.

 

seafoam done correctly will NOT hurt your new plugs, all it needs is a good burnoff drive
to prevent carbon from baking onto the new plugs-- when done via vac port at TB.

Alternative seafoam: add 1, 16 oz can to 8 gal gas/just under half tank.
run thru like normal, with more than 30 minutes at a time drive when possible for max results

Next tank, when down to half-- add another can of seafoam and run thru

You have done a more complete job than just vac port, all is clean!!
Note: Clean TB air plate by hand as usual and ck pcv valve operation/clean-lube

 

most honda cars and bikes I have seen over the years came with ngk installed,
with denso as the other approved option
(denso for the TL cost more and last fewer miles than ngk-per fsttyms1 with 400,000 miles on his TL! thats a few plug changes)

 

the mechanic the previous owners took the car to had put in the g power plugs that's why i was wandering they look fine, but i think i may change them out anyways to the IX