Weather can affect boost greatly. The hotter it is, the less dense the air is and thus less boost. An MBC is not a set it and forget it type thing. You'll have to make adjustments based on weather conditions. That was my reasoning for getting a Blitz SBC-ID. I can adjust everything from inside the car. The Unichip doesn't regulate boost. . that's why you have a MBC with the Vishnu setup. IIRC, the TurboXS Unichip has a boost controller on it due to the harness setup that they use, however, they still include a ABC so that the user can play with the boost settings. Boost spiking is usually not too good, but as long as you're not overboosting to 20+ psi or something, 16 or 17 psi should be OK. Boost spiking is something that usually happens with MBC's. Turn down the MBC a little to minimize the spiking.