I have had the Pulsar Plugs installed for a little while now. I believed there was an improvement in power. I also balanced the throttle bodies at the same time. There was a huge improvement in throttle response. It runs so smoothly from idle to redline. No hesitation, quick responsive throttle. It really felt like a new bike. I can't say which improved the bike the most. I am happy with the plugs so far. They are guaranteed for life. Time will tell.