Hi Doug.

I am with you as far as the addition of a sub goes, but depending on the factory speakers, you don't gain much by replacing those. I tried it (actually my installer tried to convince me to buy new speakers and installed them ahead of asking me about it), and while the sub was a great plus in my VW Golf III (with the best available stock audio system), the new speakers by themselfs didn't add much. New cables to the stock speakers were necessary though.

Anyway, I recommend to add a sub, but if you are satisfied with the stock speakers, I wouldn't waste any money on replacing those. But make sure you use decent cables to drive them. If you really want a top end audio system, you can't get there without replacing the stock speakers though.

cu,
sven