carb setup after changing gas from 25% nitro to 16%

[tuneboy]

Hello,

i bought a Savage X 4.9 second hand.
It was setup with 25% nitro. Now since this year, due to stupid german law, we are restricted to buy fuel with a 16% nitro at the maximum.

So I'm new to the nitro world, so, if i assume the car was set up good, and nitro is co2 so to say. I now need to lean the engine out, since i have less co2 in the cylinder? Am i assuming that correct?

Thanks!