Only 41,000 miles but thought it was a good cheap maintenance item and I was itching to get my hands dirty.

Used the original NGK Laser Iridium's,ordered from Amazon. Got the socket from Sears online, all good to go.

I didn't have much expectation since miles were relatively low for spark plug change. so far with 1/2 tank gone I can say that my fuel economy is notably better. My miles driven + distance to empty is typically around 490 miles, but now around 510 (theoretical). I keep a record of MPG so lets see where it lands after a refill.

The car does respond and idle a tad better, but its hard the discern. If you've been debating chaning your plugs I would go for it. Don't wait for "100k".

The old plugs didn't look so bad, even coloring. Here are the pics.

 

Those aren't bad at all, you should've seen my plugs on the M5 after 35k miles...

 

Actually it's 60,000 miles before you're supposed to change the plugs in a MCS, the bone stock MC you change plugs every 100,000 miles. That's what it says in my manual.

 

I changed my set out at 55,000 miles and felt the difference. Smoother and torqy.

I got OEM NGK for $12 bucks a piece off ebay, and for the money will be changing every 30,000 miles at max...less if I feel like it.

 

Changing mine this weekend, im at 45,000 miles.

With my evo I had I changed them every other oil change and had 2 steps colder

 

I did mine at 40K also. Did you measure the gap? I had one plug at .038" and the others were in the low 0.03x range.

Gapped new plugs to 0.028" and it's good to go.

 

OEM NGK's were 12 $/piece!? .....man I just got Brisk racing silver plugs for 13 $/piece gapped them to 0.019" and my MCS is running like a champ... much more responsive in sport mode!

 

Do you mind sharing where you got Brisks for $13/ea?

 

with few thousand on the plugs my mileage now sucks. Not sure if the plugs are it. I will remove and inspect soon.