Triply Periodic Minimal Surface (TPMS) structures have demonstrated significant potential in several applications due to their tunable mechanical response and orientation-dependent behavior. While orientation grading enhances structural performance, the transition zones between differently oriented regions introduce geometric discontinuities that may generate stress concentrations. This numerical study evaluates the modeling parameters of the orientation transition zone in a Gyroid TPMS structure to identify configurations that minimize stress concentration. A 3³ Design of Experiments (DoE) was first implemented to assess the influence of three factors: the number of unit cells, the transition zone size, and the orientation angle change. Regression models were developed using both an Ordinary Least Squares (OLS) approach and TableCurve3D. To improve predictive capability, the dataset was further analyzed using a segmented 3² DoE approach. Results show that, although tensile- and compressive-based material models produce different absolute stress values, they follow the same trend, enabling consistent comparative evaluation. A strongly nonlinear influence of the number of unit cells was identified, explaining the limited correlation of the full 3³ regression model. The best configuration to minimize stress concentration corresponds to 2 unit cells, a 25% transition zone, and an orientation change between 5° and 8.75°. Reduced unit cell count significantly improves response stability and model predictability.