Renthal drilling and tapping

[WayneUK]

If you have access to an engineering workshop, I believe the proper way is to predrill the bars before tapping them. My pal on the otherhand just wound the tap into the bar and it worked out fine. I paid for the workshop process to the tune of £35 :eek . My pals bars cost him a pint in the pub. :lol  Pretty sure the 1.5 x the tap size is the same as 16tpi, but stand to be corrected .

so he just tapped them without drilling them first?, has anyone else done it this way?