Well, I put about a foot of solid copper wire on my 350z for an antenna, that gives it about 3-4 feet more range... However it now tips really easily.
Probably have to add the plastic underneath to prevent tippage.
Next up is the telescopic antenna.
Update:
Just added the telescopic antenna (just took one out of a small radio) it's about 12" long. I now get over 30 or more feet of range. I may extend the range even further by adding my old telescopic car antenna to the transmitter as well.