sub and speaker system
 

hi i have a 2005 volvo s40 t5, good speakers but if i ever get some money i might just put some subs and possibly new speakers if it matters. was just wondering how much it would cost to have a decent sized sub ( and speakers if you recomend ill need them) and also installation...THANKSSS

I considered doing this, but as far as I know there's no pre-amp output on the stock deck, so it would be more complicated than what would be worth it to me.

My 01 has a 12inch 1200 watt trunk system, it ran me like 450 if i remember, it's been a while.

What you need to do is buy a sound converter which taps into your rear speakers and then into the amp (which you connect normally).
Basically this will filter the low frequency bass sound from the rear speakers and into the amp for the subwoofer. I did this about a year ago and it does sound much better but still not as good if you had a sub in jack but it is better than nothing I guess.
The converter is about $30 on ebay.