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2011 GS Ls3, A6, E-Force, 3.50 pulley is the only mods besides, test pipes/cats. Finally going to get the car tuned over running the Edelbrock can tune. Also I will get a set of FIC 60# installed. I have a question about the gap on the plugs, I have been using the LS9 ac 41-104 gaped at .38. The tuner would like a new set of NGK #3690 TR7IX gaped at .026-.028", why such a tight gap if anyone would know.

jamieo

Probably less chance of blowing the spark around with a tighter gap and boost.I run .026 gap oon my boosted truck but I see about 14-16lbs of boost.Neither my car or truck likes the NGK plugs but alot of people have no issues with them.I would think the 41-104 plugs would be fine.

Spaceme1117

If you are running the LS9 plugs at the stock gap of .40 or .38 you are perfectly fine. No need to change plugs or run a tighter gap.

With a 3.5 pulley you are not running a huge amount of boost. You are probably at 6 to 7 psi with that pulley size. If you were running a lot more boost AND your car was having issues with misfires, a tighter gap would be appropriate. Typically, when you start getting in the 20+ psi of boost, a tighter gap is needed.

I also have an E-force on my LS3 GS. It is an M6 car and I am running a 3.25" pulley. My boost max's out at about 7.5 PSI. And I am running LS9 plugs with the stock gap. Have not had any problems. And the LS9 plugs with the stock gap is what my tuner recommended.

Not going to judge your tuner, but some are good, some are bad, and some are top tier.