[DanRealtor]

The 90mm TB is designed to allow a greater volume of air to enter the intake manifold. You MUST tune the car to the correct air/fuel ratio with the TB installed to maximize performance gains, and to protect against catastrophic failure from running too lean. While even a relatively stock car can benefit from this mode (and a proper tune) this mod is especially helpful for those who are trying to move more air as a result of larger displacement (392/426's) and/or those who are doing significant porting to their manifolds and/or heads. While not a cheap mod, it is a worthwhile mod for those who are pursuing ever faster #'s.