i have a '99 SE. I had a Bose HU. I am not sure if the speakers are BOSE. Now I have a Pioneer DEH-P4400 HU. I did not replace the speakers.
I am looking for clarity and bass from the speakers. Do I need an amp to power all four speakers?

I am deciding if i should go with new set of speakers (with an amp?) that will give me bass.
OR
1-12" 500 or 600 watt sub and amp (Diamond Audio or Eclipse) from DON.

I will be spending around $600 for the sub/box/amp from DON.
BUT, as of now, I am pretty happy with the trunk having space. I had 2-12" kickers before and i didn't have that much of a room in the trunk.

 

You are not going to get much bass from 6 1/2’s that fit our maxima, either get a sub or put 6x9 in the back.

If you value your trunk space I suggest you get a jl 10w6 v2 it’s a small sub with a lot of thump to it.

 

I agree with kgb006 on the w7v2 except i would say to get at least a 12". as for speakers check teh freq response. if you want some good 6.5 speakers for a good price check out the jl vr series or the focal access line. get components over coaxial/triaxials of course. if it were me though, i would get 2 jl 12w3s. those subs make some real noise with great accuracy. for the perfect config you should set your sub crossover to just where the 6.5s start. for example:

the jl VR650-CXi freq response is 59hz-25khz so you would set the crossover on your sub amp to around 59hz to achieve the full range of sounds. also most component speakers are designed ONLY to be used with a sub.

one more thing... don't cut corners to save money you will regret it and end up spending more later. i know this from experience

 

I have eclipse components in front and eclipse point source in the back. The fronts are amped. Not much bass at all. i think I got more bass fom my bose setup.

Get a small Elemental Design subwoofer. Try the ED8, and you will get a good amount of bass.

 

Any Focal line has much more bass than most component lines.