stronger valve springs

[ppalan]

Hi,
Are there stronger (ie with more tension) valve springs for a YEB-321s? I'm currently using the normal ones listed for my horn. I got some new finger buttons but they are bigger (and heavier) than the originals.The valves don't pop back up as quickly as they should even after oiling. It works ok for a while but they need oiling more frequently than before. And yes, I do clean them on a semi-regular basis. I'd like to use Bloke's new buttons but I don't think they will fit my valve stems. Thanks in advance for any info.
Pete