Macbook 5,2 RAM Upgrade

Hello, I saw that Macbook 5,2 (A1181) and Macbook 5,1(Unibody) have identical hardware except the RAM type.
I was thinking since I was about to upgrade the factory RAM why not try a faster one, like the 5,1 since both have 1066 MHz front-side bus processor speed. So 1066 MHz DDR2 instead of 800 MHz DDR2 would work for Macbook 5,2 or is it limited to somewhere despite the processor ?
Thanks in advance!