On my P11, the end result of these modifications was trigger travel of 0.55", negligable overtravel with the trigger breaking just short of contacting the grip, and trigger pull force of 6.5#.
The trigger job permanently modifies two parts, the trigger bar (260) and the hammer (271). The hammer spring pin (273) is replaced with one you make. (See
http://www.kel-tec.com/new_page_2.htm for the parts list.) The modifications should be done in the order presented below. Before starting, be sure that you're intimately familiar with disassembling the pistol all the way down to removing the frame from the grip, the transfer bar, the trigger bar, and the hammer. Reassemble, then do the whole drill again and again while studying the parts until you understand how this ingenious machine works!
If you don't have a fair amount of mechanical aptitude, mechanical skill, and patience, don't do these modifications.