ok some links.
Hitec Agressor crx
Hitec HFS 03mm Reciever
Hitec Flash 4 Pro-car transmitter
Info on duel conversion being used for cars.
Dual-conversion receivers have been used in the RC airplane hobby for years; now Hitec has brought that technology into the RC car hobby.
A dual-conversion receiver sends the signal through two filters instead of one, and this provides better reception with less interference-that's especially helpful for gas racers. Only Hitec's receiver crystals can be used in this receiver, and it's on the large side, but the extra security of two filters makes up for these inconveniences. Two versions of the DCX are offered: one for JR, Airtronics and KO radios and another for Futaba and Hitec units.