tweaking Polk speakers

I have a pair if Polk RT55's I'm giving my son when he goes away to school next fall and I would appreciate any(sincere)suggestions those w/knowledge could offer (i.e.- from replacing crossovers and/or other internal parts to replacing a driver or tweeter) toward making these sound "higher end", if it's even possible or worthwhile. I am obviously not well-versed in this area, but artistic & good w/a soldering iron, so I would need to be educated & walked through this process. The speakers will be bi-wired/bi-amped through 2 Parasound 750A's from a Yamaha RXV2095's pre-outs, and a Pinnacle Baby Boomer will manage the low frequencies. Thanks for any help or any specific links or names of reputable "tweakers" in my area (MA). This is the only website I trust. Happy Holidays.