jellybean,
You seem to be very keen on the topic of synonymous SNPs. I stated I didn't have a reference at my fingertips as it came form a journal club of a paper a few year ago. I suggested how one could do a google search to research it and get information if one was interested. To illustrate this I did a quick search and came up with review. I didn't say it was the definitive proof. It was just an example.
If you took a few minutes you could find some examples. It is a trivial thing to do a google search, but for some reason you seem unwilling to do it. Here is another product of a quick search. Now if you don't like them, do a search and report back to us what you find.
Synonymous mutations in the human dopamine receptor D2 (DRD2) affect mRNA stability and synthesis of the receptor
Hum. Mol. Genet. (2003) 12 (3): 205-216.
doi: 10.1093/hmg/ddg055
A synonymous polymorphism of the Tristetraprolin (TTP) gene, an AU-rich mRNA-binding protein, affects translation efficiency and response to Herceptin treatment in breast cancer patients
Hum Mol Genet (2011) 20(23): 4556-4568