Here's a quote from one of the frequent posters on the Akai mailing list:

MPC3000 takes as follows:

Option 1:
2 megabyte = 1 x AKAI EXM3002 memory board.
OR:
2 megabyte = 2 x "1 megabyte 30 pin non parity, non composite SIMMS"

Option 2:
4 megabyte = 1 x AKAI EXM3002 memory board and 2 x "1 megabyte 30 pin non parity, non composite SIMMS"
OR:
4 megabyte = 2 x "2 megabyte 30 pin non parity, non composite SIMMS"

Option 3:
8 megabyte = 1 x AKAI EXM3008 memory board.
OR:
8 megabyte = 2 x "4 megabyte 30 pin non parity, non composite SIMMS"

Option 4:
16 megabyte = 1 x AKAI EXM3008 memory board and 2 x "4 megabyte 30 pin non parity, non composite SIMMS"
OR:
16 megabyte = 2 x "8 megabyte 30 pin non parity, non composite SIMMS"

OPTION 5:
2 x "16 megabyte 30 pin non parity, non composite SIMMS".

When maxing the RAM in an MPC3000 to 32 megabytes via the last option it is recommended to remove any original fitted EXM3002 or EXM3008 memory board. Lots of technical reason about this which I will not go into for the sake of
keeping this post on topic. AKAI EXM memory boards can be substituted with MUTEC ones if necessary.

Rohan.