If I set my 668 to use my zip code, it loads up a huge amount of stuff that I don't want half of. I did it only to make sure it worked ok, and then went into iScan added just the systems and stuff I wanted and even then deleted duplicate after duplicate freq (With different PL tones on each one, for every med channel in the area. I just want to hear it all, and scanning like 20 154.430 entries is crazy). For some reason, there were duplicate after duplicate of many rail frequencies loaded too, there were at least a half dozen of some of the main NS and CSX freqs added. Getting rid of all those copies sped up scanning a lot. Probably the best thing I changed on the 668 is the antenna, the RS/GRE 800 seems to be my all around best with the Diamond RH-519 a close second, with an unknown 10" duck I found a couple of days ago in my junk box being the best on VHF and UHF, but 700/800 is down quite a bit. At work, the 10" duck causes the 668 to become almost useless, with all the RFI, it is nearly silent, but outside, the trains and stuff come in very nicely. My telescoping whip appears to desensitize the 668 at home, let alone work. Works great on my Pro-106 at home though. I would like one of the more "adventurous" users here see if possibly painting the inside of the 668/1080/800 with copper paint would help with the overload as my 668 seems to pick up signals through the case, as my discone in the attic at home is ok, unless I have my printer turned on, then it just gets totally trashed with an odd hash noise on many many frequencies, my PSR500/106 are almost totally immune to the hash on the same antenna, which is right above my PC in the attic. I wonder if a slight sensitivity drop, a couple DB would help too. The sensitivity to RFI any RFI is my main complaint on the 668, I like it a lot, the rest of it's issues are minor, like the display light needing to be on to see it in anything but a fairly brightly lit room..