My pipe kit as a 12, 14, and 16 inch front. When I play speedball I use either the 16 or the 12. If I want to push in bunkers to get angles I use the 16, if I want to be tight I use the 12.
Wouldn't drop below 12 though, you start losing enough efficiency/accuracy/marker capability to make it a bad idea.
When I play woodsball I find the 14 is the best. With a 13ci my set up (also shoot a Kaos Pump with woodsball) is tight enough already. I find the 14 (with good paint bore match) gives me AWESOME accuracy, amazing consistency, and allows me to get way more shots out of my 13ci (bore match plays a big role in that).
I'd get the Lurker, and later on a decent barrel kit (Pipes can be found cheap, I love em).
The Lurker is a great under bore barrel, if you wanna go short 12inch is fine. But a kit allows you to switch up both the length and the bore, which is much more useful then a single nice barrel, particularly for use pump players who need the extra accuracy of a good bore match, and don't want role outs.
But the .678 is a great single barrel to have aside from the huge stock barrel on the KP. The stock is a decent short barrel, better then most stock barrels in that price range. If the paint is too big for your Lurker the stock will shoot it well imo. But a barrel kit (thankfull A/C threaded) is the best Upgrade you could ever buy for you KP.
Edit: Mines more experienced in this question then mine have corrected me, apperently I am incorrect in claiming dropping below 12inch decreases performance, though i'm confident about efficiency.
Last edited by 99BPS; 01-24-2013 at 10:14 PM.