I currently have a 300ex and I am looking into getting a bigger quod. I've narrowed it down between the 400ex and the ltz 400. I know the ltz it liquid cooled and the 400ex is air cooled but will that make a difference

 

Stock, the Suzuki makes a bit more power and will be a better jump up than the EX. It also handles a bit better and has better suspension as well. More so on the newer years. Nothing wrong with the EX either, just the Z beats it in most categories. A Z generally will better tolerate things such as higher compression and the larger big bore kits later down the line if you ever decide to go that route.