Thanks in advance for any 2 cents you can throw my way.

Like the title says, is it really necessary if I only got 15% and CAI at the moment. Most of the time I shift @ 3500-4500 in the city and cruise the freeway at 75-85 in 6th. The idle is smooth and no yo-yoing with stock NGK's that's got 10k on it. Right now the temps in socal is perfect for the s/c especially on my way to work at 5am. I just got the pulley this January. I have yet to find out this summer if we're going to have that heatwave again, then maybe I can use a 14LGS or BKR7. I drive my 05MCS for 4 days/week totalling 280 miles then the rest of the week an 06MCSa with 18k on it.

Not trying to be cheap cuz I change my plugs every 15k. was just thinking whether I should stock 1 step colder plugs just in case. Thanks for taking the time to read my long thread. Thought, maybe somebody's got the same dilemma.

 

In a word, 'no'.
Though I went ahead and went one step colder when it was time to change plugs. IMO the range has more to do with driving style than ambient temperature, but I'm no expert.

 

My wife's MCS has a 15% pulley and the stock plugs with no problems after about 30k miles.

"Hotter" or "colder", as they pertain to spark plugs, just describe how well the body of the spark plug conducts heat away from the spark plug tip. A "hotter" plug won't conduct heat as well, so the tip stays hotter, while a "colder" plug conducts more heat away so the tip will stay cooler.

An engine with a supercharger reduction pulley will generate more heat in the combustion chamber than a stock engine when being driven aggressively, so that's why you see the recommendation for colder plugs - to help pull away the excess heat and keep the tip at the appropriate temperature.

But if you're checking your plugs and not seeing any signs of overheating at the tip (cracks in the ceramic insulator, a "glazed" appearance at the tip, etcetera), then you're fine with the stock plugs.

I would only consider colder plugs as a "must do" in conjunction with a reduction pulley if you're driving at high RPM for extended periods of time (like racing).