100 octane stand alone
I'm running a forged 370 with 10lbs of boost. 9.5:1 comp.
My question is, would it be any benefit to run 100 octane with a 75 - 150 shot in a stand alone while the car is running 91 octane or would this present tuning issues?

Of course there will be. It will be a little different than the typical setup you will find while searching probably.
This will eliminate tuning issues aslo, not create them. You can make changes to the nitrous while never touching the PCM for anything other than timing. It will also give you a fuel pressure regulator to give another avenue of adjustment.
In your case. I would go about it like this.
Tune the car on boost. Pull out 6-7 degree's for the nitrous. I would probably run a 8# heat range for anything up to about a 125, then I would step colder one more time.
The extra octane should allow you to add back quite a bit of that timing if not all of it on the smaller shots. We will have to see what the plugs say. This is especially critical on FI since the tuneup can be very aggressive as is. Having the octane is going to make safer, and more power once tuned properly. Octane is your friend in a Dual power adder setup.


