Hi Kirk; shortening (a la 3U method - same as I used) the wires is a good thing, but you have to make sure the solder joints are good, and that the physical length isn't changed significantly - so measure the tip-to-tip distance carefully before unsoldering). Coiled wires give losses, particularly where they're close to wires carrying significant load; shortening them is good, but you have to make sure that you're careful.

For my FLARM A antenna I used a centre-fed dipole with a nice cable from amazon - "RP-SMA Male to RP-SMA Female RF Connector Pigtail Cable" which is just the right length for my installation. At some time, I'll replace the ADS-B antenna as well, though I guess I'll need a ground plane since no dipole is available. The transponder/ADS-B signal is so strong, I may just stay with the factory antenna.

Distance between antennae and distance from other transmitter/receivers (GPS for example) also can affect FLARM range. I turn off my cell phone in flight since it is pretty electromagnetically 'dirty' and bothers my radio and GPSs (I was involved in EMC/EMI avionics testing and had access to state of the art testing equipment).

Your reported ranges can also be hugely affected by the installations of other FLARMs you are interacting with... so Ramy's RF ranges may be their problem, not his. Are they old Portables?

So, what I was saying was the latter - it's a matter of ensuring you do it properly. Buying the pig-tail for about $5US and the antenna for about 8 bucks was economical, and I picked up a bit of gain from the antenna change (1.2dBi according to the datasheet); it also looks a lot nicer, which should count for something!