Depending on your camshaft config and timing, more horsepower. The 790s made their max power at 7400 rpm, while the 865s maxed out around 6800.
From what I've read, if you want to increase your performance on the later models, get more agressive cams and get Pieman to increase the rev limit and advance the timing profile.
PS - Just received my CDI unit today... now all I need to do is wait for the snow to disappear...April...sigh...
