For a step input, the final output value \( y_{\text{final}} \) is given by:
\[
y_{\text{final}} = \frac{20}{90000s^2 + 240s + 1}
\]
Using the step input value and transfer function to solve for the observed maximum value of \( y \), we get:
\[
y_{\text{max}} = 102.4
\]
Thus, the maximum value of \( y \) is:
\[
\boxed{102.4}
\]