Conclusion: Just bought and installed JL speakers on my Hayabusa as a replacement for 4" Infinity reference and they out perform reference speaker by far. Using a 2 channel 300 Watt Rockford Fosgate amp to boost the sound and with a little tweeking of the amp they loud with crisp base. Excellent buy!!
Summary: I am very happy with the speakers. It was worth every penny and the time to put them in. I also put C5-525 speakers in the rear. I can drive in my Lotus-Elise with the sound turned down and hear every nuance of the music. I have not replaced the original head unit and the sound is soooo much better than the original speakers. I wish that I had replaced the speakers long ago. I had no idea that there could be such a huge change in sound.
Summary: For all of the folks who want a clean, rich, full bass tone - these are great! I have 1" tweeters in the doors and 3-way 6x9's in the back dash. After I installed these I get a bass sound that fills the car. It completes the sound. I've seen people write about sounding tinny but I think they are finally hearing notes they hadn't heard before.
Pros: Fit perfectly - wired in parallel with door tweeters coming off a four channel amp. This makes wiring and power supply simple and effective.
Cons: I would like to see them handle about 5-10 more watts and come without a tweeter.
Summary: I hate to say this after spending this kind of money, but the factory speakers in the rear of my 2011 Chevy Express van sounded better than these. I realize that, due to the cavernous space, a 4" speaker won't provide the performance of a larger speaker, but I was expecting more than what these provide. There is no bass response and an overall tinny sound from these speakers.