Middle and high frequency vibro-acoustic simulation of complex shape insulators requires using 3D poroelastic finite elements. This can be applied to either the whole part (up to 2500 Hz maximum) or through singly curved pre-computed Insertion Losses (up to 5000 Hz maximum) to be introduced in large SEA or energy-based models. Indeed, a dependence of the Insertion Loss slopes of noise treatments following the curvature is observed both experimentally and numerically. Beyond frequency range limitations, poroelastic finite element simulations following all curvatures and thickness 3D maps typically take too much time of up to a few hours each. A cylindrical Transfer Matrix Method spectral approach significantly reduces the time for the calculation of singly curved Insertion Losses up to 10 kHz to only a few minutes. This simplifies enormously the SEA modeling effort enabling easier, more precise fully trimmed vehicle middle and high frequency vibro-acoustic simulations. A dash insulator Insertion Loss numerical validation case will be presented comparing the different methods.