No fitting required. I purchased both of mine 2nd hand. One for my k40 and the other for my K9.. I never fired them side by side with and without the ported barrel. I will say that my K40 with the ported barrel shoots softer than my single and double stack 9mms... Even my M&P 2.0 4" 9mm...
I still want and WILL have a T9... It will be a range and IDPA gun. For carry, I like my K40... I have a small frame though and am on the shorter side... If I was over 6 foot, and could conceal it w/o printing, I'd probably would carry the T9.
If I were you, I'd just get both on the used market... Got both my K40s for around $300/$330.. One NIB and the other used. I got my K9 LNIB with night sights for $500. I think I could have got it cheaper, but I didn't haggle. Seen used K9s go for as cheap as S400.