I replaced bypass caps with elna silmics, and I am very pleased with the results. The bottom end has tightened up, and I find that the overall presentation appears to have more "authority". They take a while to burn in, sounding pretty good at first, then doing some really wierd "underwater sounding" type crap for 20 hours or so. Mine have about 65 hours on them and I am completely enamored with my quickie now.
I also installed an alps blue pot for a while, 30 hours or so, but ended up removing it because it sounded darker and more restricted than the stock pot. I replaced that with an audio note from parts connexion and found it to be vastly superior in my system.
Another thing you might consider is modifying your amplifier so that the quickie is a better match for it. I installed some 180k ohm resistors, under PJs suggestion, at the amplifiers input and it has made all the difference in my system. I splurged a little and had texas components make me some custom nude z-foil resistors for this... all I can say is that now I understand what all the hype is about.