First of all I have to say that I know nothing about audios so I do not know what to choose and how to install it.
I have a 98 A4 with BOSE system and the bass id just boomy with the current stock setup. Even though I keep it at 0 level. I blew my rear speakers 3 times so far. I listen to Dance music if it makes any difference. I heard of people adding a subwoofer so my question is how to do it and what brand and size to add. Do I have the flexibility of taking it out of the trunk if I need the whole trunk? What kind of an amp ahould I add? How much money am I looking at?
Please help me out, and consider that I do not understand if you be too technical.

1. add an external amp to your current bose and fine tune the bass response to get the nice clean sound witht eh stock bose speakers. (this is what i am currently doing)

2. purchase a set of free air woofers and have them custom mounted tot eh rear of the car. (purchased 2 jl ib4 12" woffers need some more cash to have them installed. est is 320)

I did the amp install my self which took about 5 hours due to all the wiering of the bose. i also relocated the bose amp to the left rear seat in conjuction with the alpine amp i used. the rear bose speakers are currently hooked up to hte alpine amp. when tuned right the speakres sounds 100% more stronger and cleaner bass than the bose amp. the bass is cleaner w/the new amp. i would recomend this first then see if you still need a sub.

E-mail me if you have any questions.

Well if you listen to dance music then you're only a stone's throw away from what I listen to. I listen to house, trance, and drum & bass so I take it you want something very clean, accurate, and hard hitting. I have gone through 4 different subwoofers and 4 different enclosures (all sealed - because that's the way to go IMO if you want accuracy) and I finally settled on a Boston Pro Series 10.5LF. It's a phenomenal sub and requires a very small enclosure (won't make you sacrifice too much trunk space) and compared to the 3 other JL subs I've tried, it plays my house/trance music best. I have a 10" and I've tried a 12" but in my opinion, the 12" are too much, they don't recover as well as smaller diameter subs and are too boomy. In fact, I think the JL subs in general are too boomy. They're awesome for Jazz music and classical because they have a fuller sound but for fast bass hits found in techno, the Boston kicks ass. Oh, and you'll need a good amp. Be aware though that the smaller the enclosure, chances are, the more power you'll need to feed the sub. The Boston sub I have is very power hungry and I feed it with a 125watt Xtant amp. I suppose I could give it more but I don't want to make my nose bleed. Try some subs/amps for yourself... most shops will always let you return and exchange, so experiment - only your ears can make the true decision. Hope this helps.

Larry
99.5 1.8Tqts APR K&N