At my first event(This was my second ever) I was put in DM by the guys that were setting up course work. So I stayed there for this event. I am a novice, what can I say? Novice means I am new at this.
I built up a car for the GrassrRoots challenge. It was a free junker built for less than $1500. Because the challenge limit was $2004(At the time of the event, which I DID NOT HAVE THE MONEY TO ATTEND, there was less than $1000 in the car) Some of the stuff I did, like strip the car, have put it into a class that makes it very uncompetitive. While it is not a big deal, I do find it amusing that taking the foam cushion out of my car, based on(
http://www.odr-scca.org/DIY-classing.htm)puts me in class with cars that have to be trailered and have many thousands of dollars in them. Believe me, if I made lots of money I would be more than happy to try and build it to the level where it would compete, however I lack that kind of money.
So,... Looking at the DIY ruleset, it appears that putting that foam cushion(That matches the front seats as IT IS the backseat for the car) back in, will put it in a prepared class, probably F prepared.
If that is a problem then I have no problem with the personal satisfaction of owning a 25 year old car, I built up myself, that will beat cars costing many thousands more, with modern suspensions and twice the displacement.