My Brise alternator failed recently on my R300K and Brise didn't have one in stock so I bought an equivalent AC Delco version (it looks identical). Fitted it and all seemed fine. However, I have now noticed that around 5000 rpm and above, the red ignition light comes on. I am using exactly the same pulley sizes & drive belt as before. I was at Track n' Road with the two Steves on Thursday and they tested and it shows that the alternator seems to be working fine throughout the rev range even when the red light comes on above 5000 rpm as the battery is still showing around 14.0/14.1 volts so the battery is obviously charging. If the revs drop below 5000 then there is no red light and again the battery is showing around 14.0/14.1. So it all seems to be working except for the red light coming on at higher revs. I'm a bit confused why this might be happening and having the red light on indicates something is wrong. Any ideas please?