I have never heard of anyone switching down on percentages of nitro before, only higher percentages. As a matter of fact, I have always heard that it was not good for the engine to change down in percentage. I am sure it could be done. If it is only 4% difference, I would not change a thing. Just take notice in the take off performance and tune the low end needle for punch. You should not have any noticable difference in the temperature of your engine to mess with the high end needle.