If you opt to go for the standard speakers there used to be a sub you could buy separate through VW accessories called something like Plug & Play. This sub from what I can remember was a similar idea to the sub which comes with Dynaudio and also goes inside the spare space saver wheel.
I personally have Dynaudio in my car and I would not go without it. Some others will tell you different. It comes down to how much you like your music and whether you like the sound quality provided by Dynaudio over the standard speaker system.
The difference I found was a greater clarity of sound at a higher volume with Dynaudio over the standard sound system. The bass is good but depends on how low the bass goes on your music and whether it is out of the frequency range the sub can manage, in which case it will clip it a bit so you don't get the full effect of the bass as with most other consumer sound systems.
If you opt to go for Dynaudio you will also have to setup a custom EQ as even though the preset EQ's are good, for some genres of music they are not quite 100% on the midtones etc,. But if you manage to setup the EQ right as found another thread in this forum the sound provided by Dynaudio is really good and as mentioned earler in this thread it is night and day (especially in clarity at a higher volume).
