I installed a Z start Pro in my 2013 last night. The install was super easy and didn't take very long. The instructions were great as well. I ran an Exp 2.0 in my last two bikes and wanted something with lighter clutch pull for this bike since it's a 250f and I'm clutching a lot more. I only was able to ride around the yard so far but today if the rain lets up I'm hoping to go for a decent ride to break it in before my race this weekend. First off it's definitely not at all like a traditional clutch and feels completely different than the EXP version. My buddy has the EXP Core and you'd never know it was ever there since the clutch feels exactly the same as stock. On the Z start the clutch lever becomes more of a toggle switch. There's only about a half inch of movement of the lever from enganged to disengaged. It doesn't make the bike feel "jerky" though. The other weird thing is when your on the gas there's resistance like a normal clutch, although it feels lighter, but when you're off the gas there's barely any resistance. If your a trail or enduro guy who "blips" the throttle constantly throught the tight stuff it makes the clutch lever response feel pretty weird, but again if you're blipping the throttle your revs are likely up and you wouldn't need the clutch anyway. I did find if you're at idle and "blip" the throttle it will flame out. My Exp never did this on my other two bikes? I tried different springs and different number of ball bearings but it still happens. If you're moving in the slightest when you blip the throttle it never stalls so this is really a moot point but still surprising to me. Other than that small issue this thing appears impossible to stall during normal riding and racing applications. It's going to take me a little while to get used to the clutch pull but honestly it's lighter and quicker to use so it's really only an upside. You could seriously run your clutch with your pinky finger, it's that light! I'm thinking of finding an one finger clutch lever to install now. I'll report back how it works in the race and I'm looking forward to the dead engine start. My bike starts great in gear so i'm just going to leave it in second, and it should work awesome. If you're trying to decide between the three Rekluse models here's my suggestion having ridden all three. The exp 2.0 works fantastic although I'm told you'll be replacing your clutch plates more often since it slips more, which is probably likely. IMO the clutch pull is quite a bit heavier than standard and if you're racing a 250f you're probably more likely to get arm pump over a 2-3 hour race. The install and setup are super easy and mine worked great. For the money you can't go wrong. The Z-start obviously takes a little more time to install. If you can check valves and change out clutch plates you can install the Z-start. The clutch pull is significantly easier, and my understanding is although more complicated is more durable than the exp long term. I have a buddy who's ran his for 3 years on two different bikes for a total of 20 hare scrambles and enduros and his works like new (B class rider). The only drawback I guess would be the clutch actuation becomes on or off but after I get some more time on the bike I may feel different. It's really not an issue since you don't ever need to use the clutch lever anyway. The Core Exp is about the same as the Z start to install, maybe even a little easier. You could hop on a bike and ride it without ever knowing there was a core installed. The clutch feels exactly the same and you can feather it or drop it, or forget it. There is no downside that I can think of. My buddies does squeal a little on startup if he takes off slow. They offer rubber o-rings that stop the squeal but since he rarely ever takes off slow it's not really a concern. He called Rekluse and they said not to worry about it unless the noise bothers him. Anyway thought I'd add my experience in case anyone was considering one!