As far as I'm aware for Subarus, Taxtrix Openport 2.0[1] is popular with modders and seems to have good software/workflow.
Through this article though I discovered the Panda[2]. It reportedly does J2534 and I wonder if this means it can use the same workflow. The price of the white Panda is attractive.
I'm not sure if Openport is still actively developed. Oh, and stay away from the cheap clones. They're reportedly not good[3][4].
Does anyone have experience with the Pandas for remapping and use as a diagnostic tool?
[1] https://www.tactrix.com/index.php?page=shop.product_details&...
[2] https://comma.ai/shop/products/panda