I'm always wary of things like this. An extra 1300 RPM sounds nice, but is that good for the health of the engine? I always wonder why the factory didn't put out some of these mods. Usually, in order to increase engine performance/production, you have to also build up the engine itself. I have never used one of these, but for a car engine, there are differences between a standard motor and a high performance motor, and I'm not just talking the parts that give it the extra power. Things like 4 bolt mains vs 2 bolt mains give it the strength to handle the extra power too.
That said, I am sure a reputable shop could give you advice. I have mention this place before, and they have always been happy to answer my questions on the phone. Try them out and see what they say. I also found them to be alot cheaper than eBay for many things too.
http://www.mrcycles.com/
Jim