Yup, great video but it looks like you hate that Merlin mate
A lot of the sputtering was because of "funky" mix/RPM/boost settings. Keep in mind that when lowering RPM the boost rises because the engine cycles slower and the air is not "sucked in" as fast as when running higher RPM.
In a few cases you were already running max boost and then started lowering RPM, this can further increase the pressure and cause you problems.
Generally speaking, the rule of thumb to prevent this is that RPM should "lead" and boost/manifold pressure should "follow:
when increasing power, increase RPM first and then advance throttle
when decreasing power, lower the throttle first and then reduce the RPM, you'll see your boost climbing back up to an acceptable number after you pull the bitch back
Still great video though and to be honest, it's nice to see videos with mistakes because they are more realistic and interesting than videos where everything is flown perfect
