Car Subwoofers

They're a waste of money.

Even when my cars bass blows?

If you get a good one, you'll need a new head unit most likely to make room the high wattage of the sub.

whats the max amount of watts i can probably have without having to get a new head unit?

Yup. If you really want to upgrade your car's sound system, invest in nice speakers. They'll give off plenty of bass and you won't come off as a douche. And they're generally cheaper.

The only thing more douchey than having subs is having subs with shitty speakers.

If you are investing in a sub, DO NOT run it from your head unit. Please, at least get a single channel amp for it. But really, if you are going to get a sub, upgrade your speaks, or at least have them running off an amp too.

I reworked the audio in my car a little over a year ago.
Front two speakers (5.25") run off the head unit
Rear speakers (6.5") are connected to a 4-channel amp
Subwoofer (10") connected to the amp (bridged)

Amp is 720w
180w going to each rear speaker
360w going to the sub (because its a bridged connection)

If you only get a sub, you will be missing the entire midrange of majority of songs. If you only listen to bass music, i mean ONLY, then just get a sub or some shit.

An amp is essential imo. The more channels it has, the pricier it's gonna be. If you don't upgrade speaks, you could set something up for ~$300-400 but don't go cheap on car audio. It will degrade down the road. pun intended.

Cone speakers (everything from midrange to mid-low frequencies) are only about 3-4% efficient, so if you put 50w through a speaker, your return in actual audible sound is ~2w. Helps to have a sub. This is why amps in my opinion, are necessary. It also helps avoid the problem of *clipping*

Tweeters/Horn Speakers (covering your high frequencies) are 40-50% efficient, so the return is much better

The bigger the driver head size, the more air you are trying to move. Having something heavy (subwoofer) trying to move something light (air) is why cone speakers are so inefficient.

So my normal speakers were upgraded when i bought my 2002 Jeep Grand Cherokee, and there was an amp that was already installed and it services all of the speakers in my car. From the way it looks all i have to do is take two of the speakers out of the amp and plug my subs into it. But that sounds too good to be true. Does this sound right or am I about to blow up my subs?