All the SV tubes (I like better than STI tubes) I've got have always worked, I may just be lucky. Putting the witness holes isn't as easy as it sounds, they are very hard metal. If they puke with Gram's new style follower and springs, get them tuned, if they don't then don't have them tuned. Just my 2 cents.
ps. You should have atleast one tuned mag from Beven, 'cause they are cool.