You must of had a pretty rough barrel. I've read about the extra velcoity but not more powder must of missed something anyway did you shoot the barrel before and chrongraph any loads to compare against what you shooting now? I'm shooting a Lilja and Bartlein 1/11 twist barrel in my 30-06 and have a Shilen 1/13 Ratchet twist in another 30-06 and thats the one I'm using R-17 in hoping it come close to my load of 59gr/IMR-4350 with 165gr bullet @ 3024fps which is one gr below max load @ 3076fps.
I have some velocities from factory loads before and after Tubbs and velocity dropped by approx 20-25 fps. Temperatures were close so I think it was the barrel and not the conditions.
The Tubbs system tends to move the throat slightly forward and the polishing compound works the throat area more that the rest of the barrel. I did not measure my throat before and after I am just accepting what others have said were their experience when measuring the throat.
Those really good velocities for 4350 with a 165 grainer I assume you are running barrels longer than my 22" factory barrel and your slower twists probably help a little also.