there is harm in replacing the hose . you might replace the one with the restrictor in it with a hose without the restrictor in it . =free boost .
anyone who is using the stock gauge can stop replying right now .
my stagea (neo motor) ran an unstable .8 bar with exhaust and intercooler upgrades . all this is common info .
the r34 does have a solenoid . i really dont know how this thread managed to dig up so many uneducated people all at once
as for the spool up its either the normal neo noise ( to do with plastic wheels) or you most likely have a slightly blown exhaust manifold gasket