I have had my WRX for almost 4 years now and I have always had an issue with acceleration in 3rd thru 5th gear. I can hear my turbo spool up and down during hard acceleration with hesitation. They engine is not coding and it seems to run fine under fairly normal driving conditions. I haven't taken into to my local dealership because they are notorious for finding "other" issues! I have no mods.
Any suggestion or ideas on what it might be would be awesome!