Balsa Geek - I get my 6V regulators from MPI. They just plug in between the reciever and the batt. switch harness. There are other manufacturers that offer these too, though my LHS carries the MPI, so I use theirs out of convinience. You can solder one in if you like, but I am too lazy for that. I just as soon spend my time on other things (like designing and building new Fun Fly designs! )

Wings - I think that you are missing the point, we run 6V batt. packs with std. servos to get the extra torque and quicker response rate. Whether you need the 6V regulator or not? Well check with the receiver manufacturers. I know people such as yourself that have gotten away with it for quite a while. Needless to say, I personally prefer to take the extra insurance and run the 6V regulator to protect the receiver and then I compensate for the slight weight gain by using the NiMH batt. packs. The 6V NiMH 1650 mA packs, even with the regulator are still lighter than a 1200 mA NiCd pack, and I get a heck of allot more flights on one charge too. IMO, it is worth it to me, though, that is just my opinion.
Kevin