What is the main differences between the Powercore 4, speed, Q4, and 4.1 slip on's? Just wondering if it's just what it's made of or something else.

The Q4 is the quietest, then the PowerCore4 is next then Its the speed and then 4.1 being the loudest. I couldn't tell a difference in power between the Q4 and Powercore but the PowerCore is noticeably louder than the Q

I was just wondering. They all look exactly the same and the descriptions on the FMF site are very vague. I wish there was somewhere to hear the different exhausts on the 700. exriders.com has an entire thread with just that. But it's just for the 400ex.

Yea I was frustrated with the lack of info on there site also, If they have the same mufflers on the 400 sound clips you can listed to them to get an idea of the difference between them