Has anyone connected a subwoofer to the standard 5 sound system? I don't want anything crazy, just a bit more bass. No recent experience with such things but I used to do a lot of friends' installs many years ago.
Me too (mine's an Infinify Basslink II. I would recommend going with a powered sub. There is a lot of information in this forum about installing one. Search for "Powered Sub" or similar. Mine sounds great... In a nutshell, just tap into the existing wiring for the rear speakers...no RCA's.
I installed the Kenwood KSC-SW10 to my Mazda5. The head unit isn't stock, but the rest of the speakers are. I am very happy with the price/bass ratio. I bought it on Amazon.com for under $150.