I've owned standard Hi Powers, and GP Comps, but don't know of a "kit". But FWIW, I've had more than one Hi Power done up with a Barsto barrel and good sights. Shooting from the bench at 25 yards, a regular Hi Power with the Barsto and good sights, is comparable to the factory GP Comp version as to accuracy in my hands. Achieving that accuracy is admittedly easier with the GP Comp version due to the longer sight radius and lighter trigger. Within my humble experience, quality 9mm bullets will produce accuracy in an accurate 9mm pistol equal to any other semi-auto pistol caliber. I believe the USAMU has been demonstrating this with their 9mm pistols for some time now. The best I have personally found for reloading are the Sierra 115 JHP, but factory Federal 115 JHPs in the 9BP, XM9001 and 9BPLE versions have produced excellent accuracy in my guns too.