I need new plugs for the IX, im not asking if they are different then the VIII like a million people do. Instead..i just want to know if A: i should go colder, and B: if i do go colder do i need to slow the timing a little and have fuel modifications (pump,rail...etc)? I have intake, downpipe, test pipe, cat-back, and licp as my only HP and torque mods. VERY soon im getting an 02 housing and fmic. Does that mean i should go one step colder?

 

you should be fine with the stockers, I'm still on them.

 

continue running the stock heat range untill you make approximatly 75-100 hp over stock.

 

NGK stock # 4901 for 1 step colder and about $41.00 per plug. giver take a few.

 

denso ikh24 1 step colder and 45 a set