This might be a common question and I searched for a couple combinations but couldn't find an answer so I'm hoping someone can help.
I just finished installing my SF intake on my 2011 WRX hatch and flashed to the stage 1 + sf 91 map. I had the plain stage 1 map for the past week and it's been fine, boost seems accurate, power delivery is smoother, basically awesome. :-)
Now with the intake I can hear a fluttering as I let off the gas and the air gets recirculated. It's not everytime, sometimes it is sharper but I can't tell if it's under certain conditions or just random. I have heard it both at lower boost and closer to full.
My car is otherwise stock aside from the intake and tune. Is this a normal sound or should I be expecting a sharper 'pssht' each time?
Thanks for the help!