I was wondering what the model of the system inside my 535 was. I tried looking through the manual and I can't get my hands on the brochure. I still have the paper listing all the features and it doesn't say Prologic either.

 

It should be a Hi-Fi loudspeaker if you are in the U.S.; a step below Logic7

 

Sounds like you have the stock system. I purchased the upgraded and can tell you that while the upgraded is certainly nicer, it is also certainly not worth the $1200 or so they charge for the upgrade. Unless you like to crank it and have been spoiled by a nice system (like the Logic 7 system in the 3 series - wow is all I can say), then you won't really miss a whole bunch.

 

Could be the terminology is confusing. I don't believe they call the better system on the 5 series the Logic 7. Instead, they call it the Premium Sound, and should be noted as such on your window sticker.