in my experience, as long as you get a decent pair of separates and don't feed it more power than what it can take, then it will sound better than stock. especially in the future when you add a high pass crossover, then you crank up the volume.

personally, if you don't have the cash and you don't intend to compete, don't buy the P12,000 and above separates, sayang lang.

you can get good separates from 5 to 8 thousand and it will be much better than stock. just remember that your stock speakers probably cost P1500 pesos lang maximum na yun.

SQ is very subjective kasi. my benchmark is clarity and lack of distortion. that is why my priorities are a decent set of separates. a sub and amps that can drive them with built in crossovers. for me, that is enough na, if you do not intend to compete or if you don't want to show off in the parking lot

andy