Does the Sonata have preamplifier outputs?
 

About to help my buddy install his speaker and amp. But he didnt get a new deck. Just the old stock one. Think it's an 08 or something newer.

So can I install the sub and amp without a new deck?

There are no pre amp outputs on hyundai factory head units aside from the aftermarket units hyundai used to install in some special editions. Not on the 2008 NF though. I would buy a cheap head unit with pre outs,