Would the 2 x 10" produce better sound? or is it just a waste of money? Cause I read somewhere, someone said there's no difference in using 1 or 2 10".

you will notice that by increasing the number of subs you will increase ur output/volume not improve the quality of the sound, in regards to 10" or 12" generally it is best to keep the speaker diameters similar in size (gradualy increasing) so keeping that in mind i would probalby go for the 10" since u posted in the sq section

I'm driving a camry, so it's quite a big car.

So you're saying I'd be better off, SQ wise, to stick with just 1 10" sub?

I also read somewhere, 12" produces deeper bass. Good for sq?

Thanks for you reply, BTW

I just found a thread that answered all my questions. plz close.

Actually, with multiple drivers they need to work less hard to get the same output, so you may notice an increase in SQ at higher volume levels. Of course with subs you dont notice an issue with SQ till at least 5% THD, usually closer to 10%...