Perry Gehenna

my S4 won't build any more than 4 or 5 psi ATM...
i've checked all the vacuum lines, i can't see any obvious leaks.
What could be causing it?
the FMIC seems OK...
is it possible the wastegate is sticking open?
can the compressor wheel be damaged thus that it is incapable of flowing more than a certain amount of air?

i am at a loss. The car sounds like it is spluttering & missing after it gets going, it just keeps revving, but doesn't go anywhere. i recently had 1900cc secondaries installed, that have proven to be untuneable, i have been assuming that they are drowning the engine when they were kicking in (with 1.9 litres of fuel per minute) is this a possibility?

Engine failure couldn't be a factor could it? i fucken hope not....

basically, is there a checklist of common points of failure i can go over? to eliminate them one by one....

fucken cars....

Perry Gehenna