[JohnWR]

This doesn't completely apply to @ScottR , since he doesn't have Monsoon, but the consensus among those who have replaced the stock amp and subwoofer seems to be that there isn't much gain there, and that the real changes in sound quality come from replacing the head unit.

Maybe the cleanest approach without Monsoon would be to source the Monsoon amp and subwoofer and fit them into the car with a new head unit.

 

[JohnWR]

I tend to agree. Which is another reason I haven’t done anything with my “better” aftermarket amp.
I did, however, replace all my speakers including the pizeo tweeters in the a-pillar with matched and filtered speakers in the doors. I Love the way it sounds even with the top down even if it isn’t “rich” like in an enclosed car.
I never actually used the stock speakers with the new head unit, so I can’t speak from experience how much better the new speakers make it vs just the head unit replaced with the stock monsoon speakers.

The speakers have been considered an incremental change, where the head unit is a step change. Whether "incremental" is worth it is definitely an individual decision.

 

[JohnWR]

I really like this idea, John. Thanks!

You're welcome.

The effort will be pretty nearly the same, but at least you know that the pieces will fit.

 

[JohnWR]

Are you saying if I have tweeters in the a pillars it means I have a Monsoon system?

According to the documentation that I have, all Skys (and Solstices) were standard with a six-speaker audio system, which includes the A-pillar speakers. Monsoon adds a seventh speaker, the subwoofer, behind the passenger seat, along with an amplifier behind the driver seat.

The surest way to know is to check the RPO code list on the inside of the glovebox door for the code UQ3.

You can also check for the subwoofer's presence, since that is the most obvious characteristic. Some cars without it still had the grill for it, so you can turn the radio volume up and feel for the operation of the subwoofer.