Good product if it fits
Crutchfield Customer Review (What's this?)
These did improve the sound of the speakers and they will definitely seal out moisture and dirt to protect the speaker. The only problem is with them being approximately 5/16" thick they can cause some clearance issues. But if they fit, they are definitely worth the money.
Pros: Improved sound. Good protection for speakers.
Cons: Kind of thick so may be a clearance issue.