How do you know what audio system you have?

[Seadweller]

I have the window sticker for my '98 Boxster, but it does not list option codes. I believe I may have the M490 stereo option, but I'm not sure.

All the window sticker says is "Hi-Fi Sound Pkg/with Speakers"....The car has dash speakers and woofers in the door....There's a leather storage unit behind/between the seats....I can't tell if there's a tweeter present in the dash speakers, but I haven't pulled one yet either....

I'd like to order the factory replacements to refresh the system, but want to make sure I order the correct dash speakers....

By the way, out of curiosity, can the M490 dash speakers (with the tweeter) be installed if you don't currently have speakers with the tweeter?

Thanks!