I have a 2004 MCS I bought used with a 15% pulley, CAI, and “Sharked” ECU. The prior owner did not change to colder plugs.

I asked the vendor about colder plugs and got this response “Though running one step colder plugs is recommended it isn't a requirement.”
So, do I need to go to a colder plug to be safe?

Any input is welcome.
Thanks

 

The colder plugs can't hurt, and probably will help with the smoothness of the running engine -- but seriously, like the vendor said, it's recommended, but not a requirement. Especially for a 15% pulley.

 

It's like buying a nice HDTV or sound system. Do you want to use regular audio/video cables or Monster gold audio/video cables? It doesn't matter either way but if you already put that much money in, another $60 shouldn't be too much.

 

The Denso Ik22 can be purchased for around 10 bucks each so its not a big $ commitment. You don't need to swap out but the day you need new plugs I would go this route.

 

i agree with the above posts. FWIW, I talked to Peter yesterday about this and he mentioned the M7 Cosworth car runs on stock plugs. I also spoke with Jacques at Bay Bridge Motors, who runs endurance races with one of their cars and also runs stock plugs. So although colder plugs are nice to have, its not a necessity for a 15% pulley.

 

Hey haulin, were you speaking to Jacques about your pinging at the time?

 

While two examples of racing cars indicate stock plugs are used, you have to consider the fuel. What octane are these cars using? If high octane, then stock plugs may be OK, even in the endurance racer.