Did you go with the 1500 watt long or short? I measured my 1100 watt and its 12", which makes me think I could fit the longer element.
What wire gauge did you choose?
I went with the short one as I wanted to get the element further away from my temp probe. So far it seems to work pretty well. Like augie said slowing the flow down helps too. I used 12 gauge wire that I got that from brewhardware at the same time.