So, here is the question:

A mechanic had offered me free labor on cleaning TBs because of the well known rough idle issue, and if I wanted to, changing spark plugs as well. My G is 2008 with only 46K miles on it. Is there enough benefit in doing it now to spend another $60-$90 for the plugs themselves?

I read all the threads on the topic and I know Infiniti recommends changing it all the way at 105K miles, however, even though the milage is unusually low, it still is a 6 year old vehicle (and 6yo plugs). I also drive the s%&t out of it daily....

If your mpg is good and it respondes to pedal input no need to change the plugs.Does your g have a rough idle? If not no need to mess with tb.

My MPG sucks because I drive it hard;
I think it responds to the pedal fine, although, I do not know if it could get better;
the G does have an occasional shrug at a stop light which actually got lighter after the cat-back.

Yea its hard not to have fun behind the wheel! When I run my x hard I get 20-21 mpg. I only use 93 octane no 10% ethanol. Get good plugs iridium. The best mpg I get is 25mpg.

I run 91 and I NEVER NEVER NEVER get any more than like 16MPG, given that I do 99% of my smashing, I mean driving, in the city.

Although, I never actually track it. But the avg MPG readout says ^^^ that

Driving in the city thats alittle low.The tb clean and plugs should give you better mpg.

Thats 1 yes

There is an ECU reprogram available for the hesitation and low idle at times and sometimes cutting off issue. If it still has the drop in idle after the reprogram, you most likely have an exhaust cam timing sprocket sticking that needs to be replaced.

If it was my car I would put new plugs in it.

I changed the plugs on my car at around 110K miles. They still looked good, and my mileage didn't really change.

So from my experience...I wouldnt do plugs at 46K miles

I changed the plugs at 80k miles, and they still looked good, almost like new.

I only paid $50 for the same OEM plugs from Denso and only $150 for the install. The intakes would have to be removed to get to the spark plugs.

I actually did the reprogram while I had my bumper to bumper warranty last year and it came right back. Although I still have drivetrain warranty till 8/31/14.

I haven't noticed any difference at all.

NO

YES! imo Infiniti was a tad irresponsible in suggesting plugs being changed at 105k. I changed mine at 90k and wowowowow, the improvement was night and day. I'll never go more than 30k without changing them now.

People saying "performance is the same at 100k+ miles" obviously haven't changed them yet. The performance degrades little by little so you don't notice it til you get the new ones in. There's a huge difference. You'll be happy you did.