Not many drive my tang but should we have a label around the gas gauge stating this warning "Premium Fuel Only". We who have tunes that is. Maybe even stating the octane our cars "NEED" this (your tune octane). Don't know but do the GTs have a label?

 

A lot of tuners give out stickers that go on the inside of the fuel door. Putting a label near the gauge cluster would add clutter. GTs don't require premium.

 

This is another thing that surprises me about my new mustang, 87 feels just fine. I don't get it.

 

There was a quote on either this forum or another about the differences between 87 and 93 octane for the new mustang and it went something like... there's not much that a 400hp car can't do that a 420hp car can :P

 

The factory tune features "Adaptive Spark Ignition" first introduced on the 08 Bullitt program. The ECU senses the octane and adjusts the timing map accordingly to give good performance, while maintaining safe engine parameters, with either regular or premium fuels.

On the 4.6, prem adds 10'# torque in the mid range. You can feel it on 2 lane twisties in the power band, but it isn't earth shattering.

With a custom tune, like the OP mentions, you lose that flexibility.

 

I received a "91+"sticker with the purchase of the track key tune. the sticker is right under the gas tank inlet when you open the gas door.

I'm sure you can find something affordable on ebay.