As a form of preventive maintenance I had my engine tie wrapped by Peter Farrell Supercars when the porting was done.  More often than not broken or fallen off hoses are the reason for improper turbo operation.  The stock hoses tend to crack and harden over time.  Replacing them with silicon hoses prevents these types of problems.  Silicon hoses are also less likely to kink which can happen to the stock hoses due to some 90 degree bends.

Approximate Performance Gain:

Silicon hoses - none (reliability mod)

The "Rats Nest" of vacuum lines which control the sequential turbos sits behind this black air chamber box, under the intake manifold.