Installed the AM/FM last week. See no difference in reception. Had a little problem with the threads not lining up. The nylon brushing at the beginning of the threads was off set a little. Opened it up with a little with a drill and it went on OK.
Not sure if those are what I replaced with or not, but mine are cosmetic only as don't really use either CB or radio, just ipod, although I didn't really get very good reception with the long whips either...reception on FM kind of came in and out, it was annoying.
I put a set on last Friday. AM/FM reception is the same. CB antenna is purely cosmetic because I have yet to use the CB. IMO they look better and as someone else has said I don't worry about them hitting the garage door anymore.
It's 12 degrees outside so no riding and mine are in a box waiting for install. I assume I will actually get better reception due to the fact the previous owner had the original one cut shorter by the dealer. The performance had to suffer.