[Azimov]

The 49Mhz cars get better range because the 27Mhz cars are much more prone to interferance. Electromagnetic fields, cell and cordless phones, radios, and the like are very close to the 27Mhz range. There are a couple of ways to increase range though. And BTW, the thickness of the antenna doesn't mean anything (the Cat5 mods you see all over the net increase range because the Cat5 wire is either cut longer or standing straight up, the thickness is irrelevant). It's the length that's the problem. One elegant solution I have seen is to replace the stock antenna with guitar or piano wire. Cut it a bit longer and arrange it to stand straight up like the larger RC cars. You'll see a dramatic difference in range. Soldering the guitar string is difficult however. Another solution is to use springs. I've done this on many cars. A spring that is slightly expanded so the coils don't touch allows you to have an anntenna that is up to 2 or 3 feet long in a smaller length than the stock antenna. I know many don't believe me, but I've gotten well over 300ft of range using springs. To get ranges like this you need to find the formula for antenna length tuned to the 27Mhz range. I can't remember the length, but I think it's around 18 feet or so. Even incraments of this length are near as good. Like 9ft, 6 ft, 3ft,. These are not exact numbers so don't quote me here. But if you get your antenna over 18 inches, you'll see quite a difference in range. The only way to do this is to coil the antenna up in a tight configuration, like a spring. Try it.
Oh, and the FET mod won't increase range at all. It just allows more current to the motor.