you are correct in saying that good 4" speakers are not available locally. the closest i came to finding a pair was a pair of jamo speakers meant for home theater system which sounded real nice. so if u must stick to 4" speakers then look for 4 ohm (hard to find) home audio speakers. if u can source from abroad, then of course sky is the limit there.
regarding the installer, try disco music in blue area islamabad. aamir over there is as good as they come. if u do come there, tell sunny over there to give me a call, i would love to see the experiment u did.