i've got an '03 wrx. seems like when i get into boost when its warm, and go to shift (clutch in, letting out the throttle to grab the next gear) i get a ~500rpm surge, almost as if the blow off valve isn't releasing the boost pressure, and its pushing the throttle body open. its in the same "burst" that a blow off would be as well.
Would a vacuum line issue be causing this? the blow off valve not getting a vacuum signal and opening up when it should? faulty valve? I'm new to subarus, but i've built custom turbo projects in the past. no mods, factory boost gauge tee'd into the vacuum hose coming off the blow off valve.
let me know if this is normal. thanks