Verified answer

Ok, the Pontiac G5 fits 5-1/4" speakers in the door panels and 6x9 inch speakers in the back. (G5 is the same thing as a Chevy Cobalt)

This is what you'll need,

1. First of all the head unit (CD Player) may (because it's an '07) be powerful enough to power the speakers, but you may need to upgrade to a better head unit. You would need at least a 50Wx4 head unit, which the stock one may be but you should get it checked out. Best head units are Pioneer, followed by Sony and Kenwood.

2. Second, you would need to replace all 4 of the speakers (5 1/4" in front and 6x9" in back) You would want something to hit higher notes, so I suggest for the front get speakers with separate tweeters (Tweeters are the really small parts, usually about 1", of the speakers that hit really high sounds. You can get these separately installed higher up on the door panels closer to your ear, because higher sounds don't travel as far as lower frequencys, thats why you can hear bass farther away.) Getting separate tweeters will cost more to buy and get installed, but there will be a better separation of high and low sounds, so better quality. And get 6x9 speakers for the back, like I said. Best speakers are Polk Audio, Kicker, and Alpine.

3. A head unit may not be able to handle the power of these speakers, so i would suggest getting an amplifier to handle the power. DO NOT get the 1 channel amp for the subwoofer that you have listed above. You want a 4 channel amp, where there are 4 different channels to wire into your speakers, and then you can use the amplifier to work more than just your subwoofer. I would suggest having 2 channels go to the subwoofer, two go to the rear speakers (since they are bigger than the fronts) and wire the front speakers with tweeters to the head unit. Best 4 channel amps are Polk Audio, Rockford Fosgate, and (I think they make em) Kicker.

4. Last, you need a subwoofer. I haven't seen the one you have listed but I know that Rockford is a great brand. If you want a whole lot of bass, you may want to consider a 12" or two 12s. A 4 channel amp will be enough to power it. Best subwoofer brands are Rockford, Polk, Kicker, and Alpine.

Some advice,

I know absolutely nothing about Infinity Speakers so you will need a different opinion if you want to go with them for audio.

And yes, as long as you go with good brands and get it installed right, it will sound awesome.

GO TO BESTBUY. I thought best buy was a pretty good store with car audio until I went, they are AWESOME with car audio. They taught me so much and they are really helpful. They can sort out everything you will need, including pro installation with a warranty. They can tell you everything about Wattage, installation and adittional things like wheather you will need a new rack installed for a new head unit and whether the current one would be powerful enough to use with new speakers.

DON'T BUY FROM CRUTCHFIELD, they are too expensive and I wouldn't trust them, if you are going to buy online go with SONICELECTRONIX.COM you can buy all your stuff there and then take it to bestbuy and still have it pro installed with a warranty!

Hope this helps!

07 Pontiac G5

The G5 is a chevy cobalt with a pontiac nose. the cobalt is considered a good competetive car. the G5 is given a bad rap because GM made it simply to shut the dealers up. GM orginally was not going to give pontiac a small entry level car, but the dealers whined enough and they got the G5. unless your in love with the pontiac look, you can probably find a better deal on the cobalt. (this comeing from a die hard pontiac fan..) you cant go wrong though with the mazda 3 either though.