How do I add another set of speakers to my car?

If I have coaxial speakers in my car, is there any benefit or detriment to adding a separate tweeter?

• My car is prewired for use of a tweeter in the front door. I have some coaxial speakers for the speaker holes in the back window area and also for the door speakers which are located directly below where a tweeter would go. So, if I add a tweeter in addition to the coaxial speakers, would there be benefit or would it cause a problem or sound bad? As a side note, I have a set of Alpine coaxials that are used in a DIFFERENT vehicle and those instructions explicitly state that no other tweeters are to be used. Thanks.

• Answer:

  they will rob more RMS wattage from the speakers so they wont get as loud then you may have a lack of RMS wattage which will make the radios internal amp "clip" which will make the sound quality very bad (static/distortion) as you turn up the volume and that can damage your speakers over time so if you have enough RMS wattage available you could do it BUT the sound quality will be a toss up because if they are not a good match for the coaxial speakers it could end up sounding kind of sh!tty