Just changed the auto transmission oil and filter on 2004 Impreza outback sport. Manual calls for 10 Q, I put in 9.5 Q and now is seems way over full? What's the correct amount? and will over full be a problem?

when you drain the trans oil pan you will only get about 3.5 qts out. if this is what you did then yes, it is way over filled.

Thanks, sure seemed like much more than 3.5Q came out the drain plug. Any thoughts?

When I drain the AT on my 2006 Forester I get right about 4 quarts of AT fluid in the drain pan. So, I only add 4 new quarts through the AT dipstick hole. Do NOT overfill your AT, it can cause a number of problems. Among other things, it can blow the seal between the AT and the center differential. That will cost you.