I know there are some old posts on this but I just replaced the OEM antenna on my roadster (probably the only mod I'll ever do) with the Honda S2000 antenna and the difference is remarkable.

Not only does it look so much better with the top down, but the reception is just as good as the original antenna. Not a perfect fit, but no one will ever know the difference.

It's rubber as opposed to plastic and the finish is dull as opposed to the shinny original. I put some Original High Gloss Armoral on it and shined it up a bit to try and match the base that it screws into.

 

I wonder if that little lip could be cut off with a real sharp knife.

 

I really don't think it's necessary. And, you might end up making matters worse.

 

IS300 antenna fits perfect, does not have the lip.

 

Do any of these short antennas IMPROVE reception?

 

All I can say about mine is that the reception is at least as good as the OEM antenna.

Best thing to do is try an S2000 antenna and see the results. Just make sure you can return it if you are not satisfied. I bought mine from a Honda dealer, and probably paid more than over the internet. But had the convenience of trying it to see how it looked at the dealership and how the reception was while driving home.