Inductive timing lights
 

Is it ok to use one of these to check and / or set up ones timing ?, I recently used one with good results (?) , the RPM's were doubled as expected , and the actual ignition timing was EXACTLY as the ECU's when the mark and pointer (series 6 motor ) line up which is whats supposed to happen , ... well as far as I know then a friend of mine comes along and says that he thinks that the ignition values also need to be halved , is this true ?? , anyone have avy experience with this ?

Depends how you set it up... With 500R and 4 coils your ignition would be seq. So your timing light would work just fine on any lead (T&L). with a dual post on L your light would read double. in that case check your timing on the Trailing leads.