It's very expensive...
It's roughly $500 worth of upgrades to bore-up.
I stuck with the 430mm barrel for mine
... Aslo, don't spend all that money on the PDI barrel, go with the Laylax 6.03, I had a PDI 6.01 and a 6.05... and the Laylax had no noticeable difference in performance and it's about half the price.