There are a lot of good reasons the rules are they way they are. Check out my recent thread on sccaforums delving into the topic, if you haven't seen it already. Exhaust is something that wears out and needs replacing, and so are shocks/struts. Today it's not a big deal to get oem, since they last so long, but that wasn't always the case. Even now, it's still a lot cheaper to get an off-brand muffler to replace your rusted-out exhaust. The front swaybar was a safety regulation on older cars, and like some other rules, it is still around because rule stability is important. I don't always agree with the classing structure, but it's still pretty good. Newbies are going to be outclasses because they can't drive, no because they're in SM. I've beaten drivers in just about every category, as well as been dusted by HS cars on cheap street tires. I'm sure there are lots of people with 3.0L turbo Contours who would lose GS their first few times out.
Just run in whatever class is legal, and compare times to similar drivers in similar cars. I often run against paltry STS fields, so I chase down the DSP guys (There's a Neon that's similarly modded to be, but on slicks, a sick E30 325i, and a semi-stock Scirocco), and a GS Cooper S that has taken PAX at some BIG events last year (maybe not this year, though, with the PAX change). They give me rabbit times to work on, since I know my car should be close. Someday I'll beat GS, STS, and DSP in raw times...
