hi guys i have a STI7 jap spec full decat sys haywood downpipe and a gtspec headers also a injen cold air intake ...just fitted an uppipe ...the car flys but at about 4500 to 5000 rpm with the glass down i hear a whistleing noise...dose not affect the car and no strange reading on the guages ...oh the cars boost is set at 18psi and is controlled with a greedy e01 boost ...i was wondering if this is normal? ...if anyone has any advice or wold like more info please let me know

It could be the turbo whistle. I've got a full decat on a MY01 WRX and I can hear the turbo until the exhaust note drowns it out :D

Steve

Did you fit it yourself, or did someone do it for you?

Without hearing the type of whistle it's hard to diagnose for you. But at a guess it's the turbo whistle.

Does it start at around 2000 rpm, and get higher pitched as the revs increase?

Just check under the bonnet and ensure all the hoses are connected at each end, just in case they removed any. And while you're there check the condition of them (I wish I had :()

Best of luck, and I hope it is the turbo