I want to upgrade the extruder on my prusa i3 printer. I was thinking about the mk7. Does anyone have any experience with this? Any suggestions on what to get?

I use both MK7 and MK8 and have good results with both.

What extruder do you want to make?

I was previously using a J-head hot end and extruder set up and was having a ton of problems with it. I ended up purchasing the MK7 extruder and so far its been working pretty well. My only complaint is that there's a lot of stringing. Is there something I can do with the settings in slic3r to prevent this?

Sorry not that i know of, what MK7 extruder do you have?