1) Probably not much, if any. The rigidity comes from the way the bars connect to the various points on the car. One hoop will only stiffen it crosswise.

2) Maybe, depending on if the hoop you buy is for an 8 point to start with.

As long as you are paying shipping, probably best to buy the 8 point now and use just the hoop until later on. Why do you want to put just a hoop? Aside from cosmetics you aren't going to get much. If you are looking for stiffening, do the subframe connector routine. They work and are cheap.

JMO,


Don