The 1G cars have a serious problem that limits their autocross (as distinctly opposed to normal track driving) potential. The variable-effort, variable ratio power steering runs out of flow at a very low RPM, and steering effort shoots through the roof at the same time that more steering wheel travel is required to produce a given amount of steering angle. The effect is so bad that if a 1G goes into a slow (top of 1st gear) or fast (top of 2cd gear) slalom, the car is undrivable.
Not all courses have sections that get you into the magic "no steer zone", but as soon as you encounter one, you'll know it in a hurry! The car simply will not transition.
Yes, this really happens. Every single serious 1G autocrosser I've ever talked to has encountered this. It doesn't happen on every single course, but it really does happen. It's typically not a problem on road race courses, because the transitions are much milder on a track course. Unfortunately, Autocross Is Not Road Racing.
Nobody that I know of has found an ESP-legal way to fix this, although as the 2G cars don't have this problem there might be a way to update the 1G cars (in ESP only) with the 2G steering components to fix this. The non-turbo cars don't seem to be affected either, there may be some update/backdate potential there too.
1G's also have issues because of the front strut suspension - see the article on diffs for more info.
Because of this, (and because I don't own a 1G and so don't feel right offering advice not based on my real-world experience) I'm not going to spend any time on the 1G tech section. If any 1G autocrosser wants to contribute to this section, I will happily take any submissions.
Note: (8 April 2000) in the 2 years I've had this page up, no 1G owner has stepped forward to add to this section. However, Eric Stemler did alright in ESP at Nationals '99, and Mike@DSS won a west-coast ProSolo in SM in March 2000, both in 1Gs.
While there's no doubt that the 2G cars make better autocrossers, it seems that not all is lost for the 1G folks.