It is the K9 Elite with the ported barrel. Yes it does make a difference. The accuracy is notably better which is tough to do because the K9 is already an accurate piece. It also makes the recoil quite a bit softer, any softer and it would be non-existent. The large 45 is a TP45 which just came in last Friday. It was a steal at $430.00 delivered from Bud's. Yesterday I ran 192 rounds through it without any failure. I was very happy with its accuracy from 21ft. Recoil and muzzle flip was much less than anticipated and measurably less than my Glock 36. Of the two, the TP45 was more accurate in my hands. Here's a pic of a 5 shot group I shot with my K9 Elite w/ported barrel.