[s-cars] @ 16psi ECU is going into Safe Mode. Norm max 21....

[Dave Forgie]

Emmett:  There are two possible solutions that I can think of:

1. You have a small crack in the Michelin Man hose that holds until 16
psi and then it opens up and dumps pressure, leading to the ECU going to
limp home mode. You need to pressure test your intake hose system
(plugging the ISV and valve cover breather hose).

2.You have a TAP chip and/or wastegate spring.  Potentially you have the
wastegate spring turned down too tight and/or you have a stiffer TAP
wastegate spring. Normal "safe" (aka "limp home") mode an OEM spring  is
about 6 psi.   Try backing the wastegate spring off a turn or two.

Dave F.