For head unit powered good sounding speakers Infinity Reference Series usually fit the bill quite well. The references have a smooth overall sound and do better with factory/low wattage power than say the Kappas. I'm an Infinity fan, so I'm a little biased, but for stock headunit power I think their tough to beat. Boston Acoustics has some stuff that will work well with factory power, but the name of that line escapes me right now. From my ear's standpoint, the biggest difference between the bostons and the reference series Infinitys is that the highs were softer (not volume but the texture of the sound).

I hope that helps,
Chris

 

I just re-read your post and noticed that you already have a HU, and want AMP AND speaker recommendations. JL, JBL, Alpine, and others all make nice amps for your car. If it were me, I'd look for a multi channel amp with a the option to bridge channels 3 and 4 have a crossover for the sub, Power some Infinity Kappa's up front, use the class D portion of the amp to drive say a 8-10" L5 Kicker. Then run some reference series in the rear off the head unit for fill.

You're imaging will be great with good power driving the Kappas up front, and since it sounds like you're not a bass monkey, an L5 8-10" would hit hard enough for what you need, and will require less power to run clean. Lastly the fill from the reference series in the back will do just as it says "fill" in the area behind your ears with sound, though the focused imaging/better sound quality/higher power will be right in front of you.

If $$ and space aren't concerns. I'd say run a dedicated multichannel for the fronts and backs, then run a good class D sub amp sufficient to power (2) 8-10" subs. The reason I would go for 2 smaller subs over 1 larger sub is the volume of the enclosure needed. If you're going to do this install with molded fiberglass enclosures, it'd be easier to do one small one on each side of the car rather than one larger one. Honestly IMHO you don't need any more than (1) 10" in a WRX unless you are specifically trying to push increased sound pressure levels for contests etc. A good clean loud system can easily be had with (1) 10 and some good separtes up front.

For the 2 fronts, 2 rears and 1 sub driven by one amp, you might look at the Alpine MRV-F450. If you just want to drive the fronts and sub off the amp and the rears off the HU, the MRV-F340 is an option or the Kicker KX550.3. I run the larger KX650.4 in my boat for my mids and highs and it does fairly well. Then for my sub I run a KX400.1 for each L512. I got a good deal on the Kickers and they do work well, but I have heard some setups running Apline power that seem to be a little cleaner for the components they were driving. Plus the all in one solution of the MRVf450 is nice. The only compromise there is that you're not getting a class D sub channel, but there are plenty of systems out there without class d sub amps that are getting by just fine.

Remember you're in a small car, and don't need a crapload of watts/speakers to make it sound clean. Just focus on good quality components that are properly powered and you'll be fine.

Chris