the door speakers are just utilization of avaialble space, never recommendable for good music.at some level they will rattle as door are metal sheets and plastic. you might have seen those home speakers and sound boxes how stiff and firmly they are built .
general rule is stiffer the box material (enclosure) better the response from speakers.
so generally door speakers are good for vocals and tweeter part.
same with subwoofers if you prefer punchy gut wrenching bass as per "market rule" go for sony explode woofers in tight bass tube or something like that just consult the local dealer about availability and other details and do update, hope fully we can figure out the right configuration here in TAI
generally there is a saying stock hu are useless and not good for quality bass and sound.
but believe me stock hu in indica vista is clarion, basic one with just two audio outs.
i have shook floors and roofs of tata service centre with the same. guys came running to ask about the hu and remaining details but they were shocked to see stock ones performing so well.
my configuration was pioneer 2 8x6 oval full speakers in 20 litre mdf box connected directly to hu and excite stereo amp in bridge mode to kenwood woofer.
well the secret lies in the design of subwoofer to enclosure , i can boost certain frequencies at my own will which resonates with car space which can knock you and outsiders off . well the excite amp was weak often used to cut off at high booms ..but i dont listen to high levels so it was ok for me.
presently i am in process of 4 subwoofer in my punto let me see how it goes.. :)