Some good information on octabe boosters. General consensus in the article is that the 3 different types of commercially available octane boosters aren't all that they advertise themselves to be and that if you really need higher octane - AV gas is the preferred method.
Adding the stuff in recommended quantities won't significantly change the % blend of fuel and shouldn't cause a miss or backfire.
I think I'd start by checking all of the normal tuning parameters, i.e. timing, AF mixture, etc. to be sure nothing has changed.