Hmm.. Got the gel seat. It IS slightly smaller than the stock one the 03.... but it's not going on that one. My 06 is currently at the dealer at home (just had it's 8000 mile service at 9056 miles) and I'll tell you what it's like on that. I'm not at home at the mo, so it'll be monday.
It's about 8mm narrower either side. But we'll see how it is actually on a bike.
Gina
03 America - Pretty stock - except the TBS wheel...

06 America - missing, presumed in bits. With it's TBS wheel...

09 America - It's very blue....