i should have remembered that.
for what its worth, depending on the lug height of the track your considering, i have almost the identical set up in my sled as far as the tunnel and the drop and roll. when i first considered the 153 as an optional track in the 2.4" lug height, i tried both 8t and 7t drivers in the 3" pitch(i was running 9t with the 2.52 and the 151). the 8t 3" pitch drivers made for tight clearance at the front of the tunnel. i then tried 7t 3" pitch and again was concerned with not only clearance, but the possibility of track stabbing be more of a factor due to the bend on the drivers over what most sleds had having more room up there being designed for the increased pitch and lugs.
after several attempts, i ended up scrapping the 153 3" theory and for fun tried a 155 with the 2.86 pitch. using 8t 2.86 drivers, there is plenty of room up front. your not choking anything when it comes to snow evacuation, and the combo seems to work well. currently running a relocated m7 153 skid with a 155 camo extreme track and 8t 2.86p drivers.
just some math that i use for comparison:
8t x 2.52=20.16"
8t x 2.86=22.80"
8t x 3= 24"
9t x 2.52=22.68
these figures represent the circumference of the drivers. may seem a bit odd, but if you use a tailors tape around your drivers you will see how correct the numbers are.
since i was using 9t drivers in the 2.52p with a 2" lug track with plenty of clearance and efficiency, it was a no brainer to stay similar with the circumferences when choosing a track and driver configuration. the camo extreme is one of the best tracks i have ever ran.
only regret, and may adjust it in the future, is i would love to try ac's power claw in the 153 on my sled. 7t drivers with an anti-stab for sure.