jafo1970

New to me 2016 Z that I had into dealer today to do the MRC ride update and 100 octane tune. They informed me after calling into GM that the tune isn't available anymore and the part number doesn't come up. I gave them a copy of the GM performance info on the 100 octane tune I got off here. Anybody had it installed recently?

snampro

I had the 100 octane tune put in my 2016 Z in February of this year, def available

I had to order it from the parts department, then schedule an appointment with service and hand them the paperwork I got from Parts when it came in.

This was my saga trying to figure it out: CF Link

let me know what you think of the MRC update, I have not done that yet but want to do it...

RapidC84B

If you do the tune do you have to run 100 all the time, or will the car retard timing on 93?

dar02081961

It will run fine on 93.
I gave a really in depth explanation in a thread some time ago.

A short analogy would be with the 100 octane tune to look at 93 octane similar to how you would look at 89 octane if you are running the original factory tune.
There are some gaps in this comparison but this analogy should get you approaching this equation in the correct way.

badhabit_wb

I run 93 ethanol free on the street and 98 ethanol free at VIR and it works great. Car runs better with the tune than it did before.