Oh yes. As I understand it there are three pieces for the Sirius radio system in Mazda cars. (1) The receiver which is made by Sanyo. This is the black box that is on the photo of our owners manual. (2) The antenna which is the piece they installed on the roof, and (3) the radio that plays Sirius, CD, AM, FM etc.
Although Sanyo makes (1) that connects to (3) so we can hear the Sirius audio, Mazda has several makers for (3) including Clarion. The only way I found out who made (3) in my vehicle was because I took out my radio from the dash trying to reset it and found out it was made by Clarion. Unless you removed your radio or the dealer told you, you probably wouldn't know who made it either.
I was recently at a local mobile electronics store and asked them about Clarion. I was looking for a gift and the salesman encouraged me to look at some other units for better quality. Again, I think we should ask Mazda to take a hard look at the companies that makes the parts in their cars to ensure they are meeting high quality standards regardless if it is for Sirius, engines, transmissions, or any part in my vehicle. I bought a Japanese car thinking I was getting better quality. I spoke with friends who own American and European cars with Sirius installed and they didn't have any problems. Apparently even other Mazda owners that at least had the navigation radio (which I was told was not made by Clarion) didn't have problems either.