It's hard to tell. According to
Crutchfield, these are what each unit offer for speaker settings:
For the X889
Sound Management System (S.M.S.): In order to optimize the sound quality, you can use the Sound Management System to set the vehicle and speaker sizes. The S.M.S. settings include the following:
Cabin Setting: Choose from Compact, Full Size Car, Wagon 1, Wagon 2, Mini Van 1, Mini Van 2, SUV, Mini Van Long, or Off
Speaker Select Front: Choose from 4", 5", 6-1/2", 6-3/4", 7", 4" x 6", 5" x 7", 6" x 8", 6" x 9", 7" x 10", or O.E.M.
Speaker Select Rear: Choose from 4", 5", 6-1/2", 6-3/4", 7", 4" x 6", 5" x 7", 6" x 8", 6" x 9", 7" x 10", O.E.M or None.
Speaker Select Subwoofer: Choose from 6-1/2", 8", 10", 12", 15" or over, or None
Preset Memory: Call Mode 1 & 2 and Memory Mode 1 & 2
For the X890
Speaker Settings: The Speaker Setting function tailors the System Q Sound Control settings according to the type of speakers in your vehicle. You may select a Speaker Setting of "SP Off" (flat), "SP OEM." (for OEM factory speaker systems), "SP 6x9/6" (for systems with 6" and 6"x9" speakers), or "SP 5/4" (for systems with 4" and 5" speakers).
My car has 6.5" speakers front and back, so there doesn't even seem to be a proper setting for it.