I meant to write this this morning... but got distracted by 2023 Prius content.
Caveats:
I am not an SCCA member.
I have not competed in XS, nor Solo... except one event back in 2015.
I have a deep-seated hatred for the Solo GCR, the Road Race GCR, and the SCCA.TT classing.
I realize my comments to follow will sound similar to the "That's not a $2000 car" comments GRM $Challenge gets.
I believe I understand the current reasoning behind the points I'm about to criticize.
those out of the way...
I really don't agree with the restriction requiring that HEV/PHEV/BEV vehicles retain OEM battery systems in a class that is named "extreme" and is intended to allow an "anything goes" approach to street-vehicle modification.
I understand that this is probably because of the concern about modifications to these systems leaving the subject cars to becoming significant fire hazards. {feel free to insert your own image of a burning Tesla}?
However, as written, this rule would seem to restrict allowing to "upswap" a CR-Z with a NiMH pack to an OE Lithium pack from a later CR-Z... or utilize an OE Civic IMA module to provide higher assist. Similarly, it would technically restrict updating a 2G/3G Prius to using 4G NiMH cells, or any aftermarket NiMH pack replacement. Further, it restricts the use of ProjectLithium LiFePo4 swaps into 2nd/3rd/4th gen Prius or various Camry Hybrid and HS-250h's. Or 48kWh pack swapping early 1G Leaf with a 'base' 2G pack.
All of these example applications will work within the existing architecture of their vehicle's EV systems, and would have minimal enhanced fire susceptibility... but are denied thanks to the lack of experience with the subject by the current rules committee... and yes, the concern that smaller regions would potentially lack the information/experience/equipment to handle an EV system change, adjudicate it's reasonableness, nor an ability to deal with a voltage induced fire.
I do expect this is currently a "niche"/"corner" case variety of concern. However, you asked for feedback... so it seems like a reasonable time/place to raise this... so that a) those of on the forum with some experience can chime in; b) the "powers-that-be" can begin considering/learning about the topic in order to eventually allow legitimate "anything goes" performance enhancements.
Edit:
Also, these rules continue to "effectively" preclude the participation of EV swaps in Solo.