Boost Problems

[Plow Jockey]

Hey guys, driving around my brothers 00 chipped S4 and having some boost problems. The car will pull really hard then dive on it's face (still at WOT). It will sometimes boost to 20psi then drops down to 10psi then holds at 5psi (all at WOT). Then other times it will boost to 15psi and hold at 10 or 11psi(WOT). Other time it goes to 15psi then holds at 5psi. He doesnt remeber what chip it has, it has brand new dv on it(dont know what brand). I just want to fix it cause that thing pulls hard and would be alot of fun to drive. any ideas would be helpful. Thanks in advance.

[2380S4]

TBB, blown hose, DV's maybe not sealed could be a waste gate as well. Boost leak some where....

[RolledMySTi]

Pressure test the car first to make sure there are not leaks. If that turns up nothing it may be your N75

[Plow Jockey]

thanks will do