i seem to be having a problem with my s2 boosting?!
the car is fine once in the norm on the temp gauge but when it reaches around half way thats when the problems start!
i feel the boost start to come in as normal but then i get alot of noise from the air filter and exhaust and i seem to have no power, if i ease off the pedal the go back on i seem to get the boost back but this doesnt always work?!
i hav recently been running a bailey dump valve and a pipercross filter, i have removed the dump valve but there seems to be no improvment.
i am yet to change the filter but could this causing the problem?!?!?!

please help