If your shooting fmj, plated, or lead coated bullets you'll do just fine with the factory barrel. I had issues with feeding in a kkm with my hand loads using truncated cone lead bullets loaded as long as i could reliably feed in my magazines, but the factory barrel works perfect. I use zev triggers, but I also hear the DK triggers are worth every penny, probably gonna try one in the future. I'll also second the dawson sights and magwell. Arredondo mag extension are nice, TT though have extra weight at the bottom to help drive the mag out during release. You will have to cut the retention pins though or just double check them every time if your using a dawson ice magwell, they hit on the magwell. SJC makes a good mag release button as well. Speaking of SJC, if your okay with sticking with a ghost holster or cr spead rescomp, then the SJC frame weight is a great addition. The biggest downfall IMO with running plastic guns in major power factor against full length metal dust cover guns is the muzzle flip from the added recoil. The frame weight really helps with that, but limits your holster options. SJC offers a mod service for the ghost holster, you can mod the cr speed with a dremel easy enough though. My two cents though to add the already good advice hear. Oh and my spelling is horrible I know.