Factory Amp Rating - Peak or RMS?
 

I am planning to upgrade the head unit and speakers in my 2001 Boxster S. I have the "hifi" M490 speaker system in my 2001 Boxster S. It has the factory HAES 4x40w amp powering the doors (bass frequency only) and the dash speakers (I think full range, but not sure). I also have the rear speakers that I think are being powered by the head unit.

I am planning to install a Sony AX6000 head unit that has 4 channels with 22W RMS and 55W peak per channel. Is this higher than the factory amp? Is the 4x40w rating on the factory amp peak or RMS? Same question for the 996 cabrio 6x40W amp. Is that peak or RMS per channel?

You can open the amp and check the marking on the ICs of the amp. Then you can take a look at the datasheet of that IC and there you can see the max power rating.

I would suspect that it's a RMS rating, PMPO wasn't a thing in the late 90ties.