what is the "boost sensor" it was on my ram air on the stock intake now its just hanging there nething im suposed 2 do with it? what does it do?

also when im accelerating at a normal rate....when it gets up around 2000 RPM's i hear a high pitched squeel kinda soft but defenately there. t sounds like brakes but its not and if i press or release the gas pedal a little it stipps till i go back to that position and it doesnt do it over 55mph and under 30.....? ne ideas?