What if in my fictional world π equals 5? What then? Does it matter?

I don't think this idea of mine is original, I've probably seen it somewhere before. But still, what would be different?

Circles have more area inside and longer circumference since S=πR^2 and l=2πR. Does it mean that the spacetime is denser somehow?

What about the waves and wave functions? They depend on π too.