Sneezn

So here is my conundrum , Here i am follow the instructions on how to hook up a mbc . No dramas at all hooked her up . But first to check my n75 wasnt being a **** head i disconnect the wastegate side and took her for a quick spin . Boom straight upto 15psi and she hit boost cut . No worries get her home and hook up mbc close her all the way and go for a drive car boost to 8psi happy days . But i change hard from first to second and once im in second gear and building boost the motor sounds like the timing has been retarted or im running on 3 cycl then i back off and go again no dramas . Keep in mind n75 hooked up factory postion it hits 5psi and holds hard a fast all gears . This is doing my head in, Am i in Limp mode ?