Depends on the outcome you really want. I am not a Goodman fan, but in their defense, the compressor that is sitting outside is probably a Copeland, like almost everything else on the market.
If you are needing to go on the cheap, change out the coil (though with an 8 SEER you will not have a matched system and this could be a problem)
If it were me, I would at the least, change out the AC system, and a 13 SEER or 14 SEER will be your "sweetspot" or best bang for your buck in relation to outlay of cash versus payback over time.
Plug your numbers in here to see a simple payback calculator.
http://www.acdoctor.com/cooling_calculator.php
Good Luck
If you are needing to go on the cheap, change out the coil (though with an 8 SEER you will not have a matched system and this could be a problem)
If it were me, I would at the least, change out the AC system, and a 13 SEER or 14 SEER will be your "sweetspot" or best bang for your buck in relation to outlay of cash versus payback over time.
Plug your numbers in here to see a simple payback calculator.
http://www.acdoctor.com/cooling_calculator.php
Good Luck