controller design and the spool up response of the turbos. To prevent boost spike either MBC or EBC will have to open the wastegate before target boost level is reached. How much sooner it opens up will depend on the wastegate design and spring pressure of the wastegate and how fast your turbos spool up once it reaches it's sweet spot. On my ball bearing turbos, boost builds up slowly until 4500rpm, then takes off like a rocket after 1 bar. I used dual port Tial external wastegate. On a MBC, I noticed temperature does effect the boost on the same setting . The colder it is outside, the higher my boost at the same boost setting on the valve.
