@Ivan
I used what I could get, and 166MHz is for the -60 version
I could have used the CL2 verison(-7E) but it didn't occur to me...
As I said, no change of nvram variables necessary(but ncdl should be cleared, se posts #33-35 in this thread: http://forum.openwrt.org/viewtopic.php?id=3892&p=2 ) the memory size is autodetected by CFE during bootup.
refer to this page for sdram variables: http://wl500g.dyndns.org/sdram.html
as you can see, 128MB would be possbile with 512Mbit chips. These are hower not very easy to obtain(in small quantities at least)
Edit: Since 32Mx16 DDR chips seems common you could possibly get 128MB if you are adventurous.....