WL-500gX Tomato firmware question

Until now I have been running Olegs firmware but recently I found out that my router can't handle the latest speedupgrade from my ISP. I can't squeeze anything higher than approx. 25 mbit downstream out of it. I tried various speedtests, torrents and usenet-downloads with up to 8 threads. When connected directly to my modem I managed to get to about 48 mbit.

This might be what we dutch consider "cursing in the church", but is there anyone that could enlighten me which tomato version (as in: highest possible version) is able to run on the Asus WL-500gX and where to download it because the Tomato site itself only serves v1.25 and 1.23 if you search hard enough. These both do not work as when I try to upload either one of them (tomator.trx) my router presents me with an error message saying the firmware is corrupt or incorrect.

So in short;
* what is the highest possible version of the Tomato firmware to run on the WL-500gX?
* where can I actually download this version? (as mentioned, official site only offers 1.23 and 1.25 which don't work)

Cheers,

JaJoah