devinplombier - guess that was somewhat dense. Let's try again.
If the 2 subwoofers have visible rubber mats on their cones, they have not been upgraded to CS5i status because the CS5i MDF plug replaced the rubber mats for mass loading.
The MDF plug looks like a small hockey puck where the dust cap used to be. Those plug drivers have the new motors, and at the same time the woofers and lower midrange were replaced with the new motor version, even though those 2 drivers look the same as the original CS5.
Rob says the 5 to 5i upgrades were all in 4-driver sets, so there probably aren't any mix and match hybrids around.