boost leak under the dash?
6.0 rushing air sound under dash that goes along with the boost guage, very hard to diagnose since u have to be pulling a hill at high speed to get enough boost to make the noise, hope someone else has seen this problem and knows the cure
Boost gauge is purely electronic so it's not your leak but I suspect you have a plastic cold air pipe on the cold side and it's more then likely cracked at the bellows under the air filter. If you have someone to assist you, have them brake torque it with the hood open and you should be able to find the source of your leak.
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