I am going to perform a compression check on my Legacy tomorrow. If it fails, i'm done with it. There is some chance that the timing belt is streched...don't know cars history. Car not running well. Will this skew the compression readings? If the belt is streched will the timing be off? Many thanks. Also what are the symptoms of a loose tensioner pulley?

Toothed belts really don't stretch enough to significantly affect your timing etc. They CAN stretch enough to affect their proper tensioning.

 

On an EA82 (haven't heard the EJ22 yet), a loose tensioner can let the belt make a whirring/buzzing noise, loudness can depend on how loose and how noisey the rest of the engine is. My GL-10's belt could be heard distinctly from 2500 rpm up, even during freeway driving. I wasn't sure what it was until I retensioned the belts and it went away.

Compression tested great. 180, 185,185,170. Can't complain about that. #4 was the 170. But it's still within the 20% variance...and within specs. No engine job here.