I could be wrong, but I don’t think anyone upgraded the spring for the reverse band servo.
The servo itself sure, as there are billet upgrades for those.
Ope sorry, I meant on my transmission. I was wondering if I needed to install the spring that came with my TF-2 kit but I decided not to and it seems fine. I got it all back together today and just came back from a test drive, no issues with it going into 1st or Reverse (or any gear for that matter) harshly.