I just finished putting a 2.2 from a 97 legacy into a 98 outback. I am getting a code po325. Didn't have that on the legacy when motor was pulled. Any thoughts

 

Also when I give it gas while driving I hear a whistle sound.

 

Thanks

Knock sensor is a common failure and super easy to change out. They can make these cars act pretty goofy sometimes. Change that out for sure.

 

As to the whistling, is it just when you are driving? Or would it make the same noise in park/neutral when given gas? Lots of things can make lots of noises, - belts, bearings, pulleys, clutch - try revving the engine by hand while looking under the hood to see if you can't get a closer idea of where the noise is coming from. - If that motor had been sitting for a while, it's likely that something got a little rusty or sticky from sitting. Sometimes it will just fade as the motor is run more. Sometimes stuff may need replacement.

check the air filter box is clipped in correctly.