Raising the rev limit on stock ECU

[gon]

yes, raising the clock of the main ECU will give you a higher rev limit but will also mess everything else on the ECU.
I would not advise this modification unless you monitor your engine very carefully using a wideband lambda sensor and a knock detection device.

If you still want to go ahead, open you ECU check what the crystal speed is , go to an electronics shop a buy the one just above and give it a go.

Read the following topic carefully:
http://www.aeu86.org/forum/showthread.php?tid=11968


The image above is not from a 4AG ecu, I think its 4afe ....
having said that , the crystal on the 4AG ECU looks about the same but longer, it is located in the very corner of the ECU (opposite side from connector). It is laying down and it has a protector cover that must also be removed for replacement.
The cover reads 4NDK71: