Would love to do this but how much over all did it cost you to go to 136/View attachment 115303 Hartman is top quality. Here's mine...has Hartman rail extensions and tunnel extension. Went from 121" to 136" on mine also.
The Hartman kit is $335. My track was only $514 shipped to my door from Snow City. I did a bunch of bearings and the extrovert drivers from Barn of parts at the same time. If you don't have them it's a wise investment. I used the cheaper set that are additional to the stock ones because they are advanced a few degrees so they are always touching the track. They work great. The sled works extremely well with this track and extension. Any more questions fire away. Good luck!Would love to do this but how much over all did it cost you to go to 136/