Hi there, just got an 05 GS500 Naked for my wife.  Been visiting this forum for info, great site! 

First question, is there a timing advance for the 05?  Is it even needed?  I read that since 04's, they are a bit different.  Thanks

The only timing advance is for the older models. The '04 got changed, and no advancer was ever made for it. You should be fine without it though.

4d

Yeah, the revised signal generator has only one pickup while the rotor has a bunch of studs on it now. I guess the new smarter ICU knows to alternate ignition signals to the right coils in addition to adjusting timing based on the TPS.

Which kind of begs the question, I wonder if doing the slotting trick might cause more harm than good by throwing off the timing an unintentional amount if the ignition mapping in the ICU already does this.

Anyone want to be the first guinea pig?

fg