Audio Systems: is this a good set up??, alpine amp, private question

Question
i have 2 12" kicker comvr's that i payed 140 a peace and a alpine amp that is only 350 watts. the subs sometimes make a wierd sound when bass comes on and it scares me a little. what is the sound it makes and is this setup ok?
    thank you, DJ

Answer
Is it a good setup:
It all depends on how they are loaded (boxwise, which you have given me no clue of), the rest of the system and most importantly, your expectations about sound quality and SPL.

The sound you are hearing could be a result of many things including the enclosure or the grounding, ect. It would be a guess that you simply have the amp gain set too high (sadly, most people do).

If you really want a concise answer, please resubmit this using the 'private question' option and let me know what year/make of the vehicle this is installed in, the exact layout of the electronic components (from the head to the speakers), wiring (including the power supply) and the gain settings as well as specifics on the enclosure.
With more useful information about the system, I can try to give you a more useful answer.

Jerry Mael