The regular gas station where I fill up was out of 91 octane fuel tonight so I made the trip to the Cenex station and added some 93 octane. I figured she deserved some better fuel and wanted to try the performance difference of 93 octane.
She was all warmed up (been driving for about 15-20 minutes). After leaving the gas station I drove back roads doing about 35 mph for about 5 miles. Then I was able to get on it and she performed fine hitting 6k in first gear and 5k in second. I slowed down to make a turn going down another slower road and hit it again. This time 2nd gear after 4k I heard a whooshing sound I never heard it make before. Almost like something was leaking (no audible pinging or knocking). I'm used to a whistling sound (I'm assuming the waste gate) when I hit 4.5k or so RPM's but this is a completely different noise.
It also feels like I'm losing some power. After pushing it some more around where I live the sound now activates at casual speeds even below 3k.
Its a 2011 WRX with less than 2100 miles. I broke it in proper and never have redlined her. Any thoughts?
Is it just fuel related since it just occurred after getting fuel? Or do I have a vacuum leak somewhere? Is it possible the BoV is releasing pressure to soon?