Have you tried a different microphone/headset? Don't take offense, but are you talking into the correct side of the mic? Don't laugh, I've seen that done! When you had the SWR meter attached did you check the power output when modulating? If so, di it show a couple of watts?
As Red inferred, a couple of Watts output is plenty, although most put out around four, I think. If you have at least a couple of watts output to the antenna, and the antenna is well matched (SWR 1:1, can't be LESS than 1:1, that would mean you're antenna is transmitting more power than it's receiving), then it's likely that you have an audio modulation problem.
Assuming you have proper RF power output (most likely), then try this:
Make sure that the "Roger Beep" is turned on (it should be, by default), and see if that can be heard in your tranmitted signal. If it can, then the problem most likely is in your headset connection. (since YOU can hear, it's unlikely, although possible, that the problem is in the wiring of the 'Wing itself) Verify by having someone plug into the passenger intercom connection, and see if you can talk back and forth. Most likey you won't be able to, in which case find out what's wrong with your headset. Note that headset microphones can be pretty fussy as to where they are when you talk into them. I've had the best luck with them out against the face shield (or chin bar on full face), and the face shield down, microphone well below the lips, so that you are talking across it, rather than right into it (especially if you tend to talk loud, which is easy to do at speed). Then you can talk in a normal tone of voice, and be heard just fine. Too close tends to clip, too far away doesn't modulate well enough to be heard.
If the "Roger Beep" can't be heard, you most likely have a problem with the CB itself. Verify, by making sure the intercom works, by having someone plug into the passenger connection. If intercom works, then problem is the probably the CB.
There are several things to check, try a different headset, one that is known to be good, make sure you are close talking the mike, the mikes are noise canceling and should be almost touching you lips when you talk, I have run into people so many times that have poor audio on send, take a look at them and the mike is 2-3 inches from their mouth, that doesn't work. Here's a little test for mike distance, pucker up, if it isn't touching the foam wind sock on the mike, it's too far away!
Here's some instructions on antenna tuning I put together.
As I remember it the michrophone input to the radio is too low, someone else may remember the details. I personally opened the CB and turned the potentiometer up that controls michrophone I think that it was VF104, I have the info stored on CD here somewhere. Now I am at the level of a GL1500 CB in conversation before in a ride with a few of each bikes the 1800's were hard to hear. I got the info on this from Louis "Carribean Wing" and it was pretty easy but probalbly will void the warranty. What the bike really needs is a preamp for the michrophone that could go inline and run off of 12 volts.