As you guys know, I am a diehard Dalton fan for a lot of reasons so in my photos you will see the Dalton Brand of Over Drive Clutch cover as I just purchased a second full kit/cover for my wife's 09 Teryx. The machined covers also accomplish basically the same thing and this thread covers what they claim to do and I try to break it down to make it easy to understand. You are going to need a clutch puller to remove the clutch and install the Machined or OD Cover either one. You do not need a spring compressor to change your clutch cover.
Here are the claims and what I have found.
1. Dalton or Machined - Increase in top speed.
Yes Top speed increases if you don't have an 09 with limiter, but more importantly for me, I get more top speed in LOW range, so now I can run up to about 30 to 33 MPH on my GPS in low without hitting the rev limiter. I ride 90% tight steep and rocky trails and use LOW range basically all the time in the woods, no need for high at all anymore.
2. Keep KEBC - Not with the Dalton as there is no one way bearing in the cap. I see a few different brands of machined stock caps that claim to allow you to keep the KEBC. I do not have first hand experience with any machined covers except for what I have read on this site and Hunterworks site, sorry.
Personally I can't stand the clunkyness and rear gear lash noise induced by the KEBC and I much prefer having it disabled. The Dalton will not let you still run KEBC, so this could be a factor for those of you who think you want the KEBC. I would encourage you to drive someones machine without KEBC and make sure you really do need/want it. The KEBC is especially clunky and hard to rock crawl with, if you rock crawl, you would love to be without KEBC IMHO.
3. Provide Extra cooling, light weight and strength for your clutch.
Only the billet covers can do this, like the Dalton and I believe a couple of others. The stock machined caps do not provide extra cooling, and they are reported to be weaker since material is cut from them. To date, I have not heard of a machined stock cap that failed on a Teryx. The billet covers are definitely a lot lighter weight, they have a big vent holes as well.
I hope this helps you understand more about the covers. I know I prefer the Dalton brand, but the basics of what they do and how they work is pretty much the same technically. You need to decide, what your budget is, if you want or need the KEBC and finally whose OD Cover or machined cover you want to buy. I go for the best parts I can afford and look for companies with the best customer service for just in case I need it. I hope this helps you understand and make a choice that is right for you. For me the choice of Dalton it is a no brainer for me and the customer service is second to none. I have seen good things reported about the Hunterworks and UTV Crap machined covers as well, but I have only had Dalton.
Here is the Stock Clutch Cover next to the Billet Dalton Industried OD Clutch Cover.
Reinstalled on the machine.