I have German Maestro's in the front and JL in the rear.
perhaps someone learned of GM's from one of my previous posts?

They're terrific speakers, aren't they?

inklove:
anywho, if you want bass without a sub, your only option is going to be to draw your bass from your front 6x9's, since theyre the only speakers in the cabin that will produce decent audible bass.
Polk speakers, IMO have a very clean, smooth sound...but they have very strong highs. For the money that the speakers cost, they're definitely a TERRIFIC alternative to the factory system when building on a budget.
The Infinity speakers, particularly the kappa line, are also very good speakers in a few different senses. Being that they are 2-ohm speakers, you don't need to feed them a whole lot of power to make them sound good. But with a 2-ohm speaker, any given amp will drive them more power than the same amp will drive into a 4-ohm speaker. Less resistance means more power to the speaker. So if you add an amp to them, you won't have to buy a very expensive amp to feed them what they would need; thus saving you some money.
My opinion on infinity speakers, though, is that their high notes are very shrill and metallic-sounding. Their clarity is outstanding in terms of the highs, but it is very hard on the ears(depending on what your ears like); and their bass is usually found to be a bit lacking(again, depends on what your ears like to hear).
Your options are very limited with best buy, as I don't think they carry very many speaker brands nowadays. But if I were to choose between the Polks and Infinitys, I'd go with the polk speakers. If you decide to spend that gift card on other things, and want to build a terrific sounding system with good components, Let me know and I'll help ya build something you might like. Seeing as how my previous super duty had been stolen with a HELLUVA stereo system in it, I'm building another monster system in the new one. Therefore, i'm already in stereo mode so ask away
