[Cupcar]

Aren't there some increases in HP due to a reduction in negative work done during the cylinder pressure cycle (because there is less timing advance required)?

Given the above, it is harder to get that last little bit of compression with a second plug drilled into the combustion chamber, could this negate the above?

If the advantage only goes to decreased octane requirement, then if one is building a track engine for use on 110 or greater octane fuel why run twin plug at all - especially when the compression obtained could be higher with a given piston, not to mention doing the job with a cheaper, simpler, lighter ignition system?

Thoughts on these points...