I have a stock ECU. Everything I've read says to set the timming at 17-19 degrees. I'm using standard 92 octane. When should I start to hear knock? Other vehicle I own (Toyotas) have very loud knock when I advance the timming too far.

When I set timming at 17, my vehicle surges between 2000-2500rpm at constant throttle. The higher I set the timming the less surging I have. What is the maximum safe timming?

That surging is probaly EGR related. Check se-r.net on it. Its pretty easy to fix.

On timing its just up to your engine. It depends from engine to engine. Safe max is usualy around 21 or so. Its been proven on dyno that usualy anything past 19 nets no real gain in hp, just slight throttle response increase. So its really not that good to go up that high but some doe it.