I'm not good enough to be overall pax competitive, I'm just trying to go fast lol. Doesn't the ESP and the rest of those classes require you to gut your interior to be competitive? That's also something I wasn't willing to do. There are some strange cars in his class, I will give you that.

As I understand it (and even though I'm a Solo Chair, I'm not a rules expert), Street Prepared classes do still require that you have an interior at least from the front seats forward.

Street Prepared (again, as I understand it) allows you to do the following things beyond Street and Street Touring:

R Compound DOT tires (Hoosier A7 for example)
Metal suspension bearings where they were not metal before
Different fuels such as E85
Aero changes within the rules

In my case, I added Flex Fuel so that took me immediately out of ST. I had a spare set of slicks that I wanted to use for track days so I decided to have some fun.

I actually looked it up and it wasn't as much as I thought but gives examples of ac removal as well as radio and airbags. It is the next logical step from stx but for whatever reason locally very few people run it unlike xsa.

Street Prepared definitely lets you make some decent mods. I doubt I would get rid of AC but I might consider getting rid of airbags if I cage the car for track driving. I'm able to run ESP this year because of the limited prep. DSP is the real class with all the stuff done. However, it used to be CSP for full prep and that's a big jump.