Hey guys, i have a question. I'm planning on buying a good radio for racing. I want only Futaba, so i can't accept other radios. So, i read a bit of these two and i can't find many data. So, i thought that you may know something that i do not. However, i wonder if these two have a major difference in performance (i mean electronics, memory, that stuff). I saw that the 4PK has a rechargeable battery of 1700 mAh. Does the 3PK has one too? Can i upgrade those batteries to MUCH MORE? Anything you know, please share it. I'm all "eyes" Oh, and what are the differences between the 3PK and the 3PKS? Thanks.