Ford Mustang V6 Premium?

Have a ford mustang v6 premium, Should I put premium gas in it or continue regular gas

Performance and fuel usage depends a LOT on driving conditions and driving style.
The only way to find out what works best for you is to log your data and find out.
My Mustang works better with 91~92 octane, but going all the way to 94 bring no benefit.

Get one of those fuel monitoring and mixing app like Econoctane ( https://play.google.com/...Econoctane ) and find out. By the way, if you buy super premium and regular in the right proportions and mix them by buying them sequentially, you can save 5% on the price of fuel compared with getting 91 straight from the pump, as the gas station charges EXTRA just for setting a mixing valve.
Econoctane was first designed to allow you to save that 5%.

If the motor doesn't ping when driving up a steep hill fast just keep using the 87 octane gas.

The V6 only requires 87 octane. If you are using premium you're not hurting anything, but you're not gaining anything other than a lighter wallet.