never done it myself but my sled was done bfore i got it. 151 x 2" ported track weighs same as a 136 1.5" that was factory on my sled. the guy that did it did it himself and cut three 1.5" holes across between each of the rows of paddles. also snow doesnt pile up on the track as bad either.
i run one hole 1-15/16 down the center, no wheels run there so doesn't vibrate. wouldn't cut holes in staggered formation either cause once you cut a thread its got no strength.
I did a double row of 1-1/4" holes in my 162" and I'd say that I removed approximately the weight equal to 2 full soda cans. I had to re-clutch as I gained RPMs and was now bouncing off of the rev-limiter. I'd have to say it was a win for me. Good luck! :d