I've very rarely used a foam or any other sort of mute while playing, only palm muting. I've been experimenting more with it lately, however I am running into a problem with tuning. No matter what mute I use - no matter what the thickness or density - the tuning goes sharp. It ends up being 10 to 25 cents sharp (depending on the density and the string). I've used weather stripping, dense foam, soft foam, sponges, chamois, etc. I even picked up a Fump (which I don't like because I feel it dampens the strings too much, with almost no sustain on the E string). My palm muting technique is fine (been doing it for 30 years), but since I use it so much these days, I figured I'd just use a mute to get the sound I want. But, I don't want to sacrifice tuning. I think the only thing I haven't tried is the BassMute because it cost too much. Any advice?