Kim,
I personnaly like the idea of a cage. It makes the whole frame stiffer for one. I even midified my sill framework to give it more strenght. My cage has its front to rear pieces in the center or the framework. I think that the only negative is that the head side to side room is the only thing that tends to get tight, and that is only when you have a helmet on. Given you have a helmet on, you should have a 5 or 6 point harness on and your head then won't hit it then unless you are one that
NEEDS a Gutrney buble. I am placing my seat as we speak. I am 5-9 and with an inch or two of seat of the pants to the floor, I have enough room. What you might notice is a little less visibility out the front windscreen(top portion). The cage for me will be a benefit, in that you will find most people who get into one of these cars and have never done so before, will grab the body just above the windscreen at the A or is it B pillar. Unless you have one of Fran's cars or an original(steel spider) that part of the body is fairly weak and will flex rather easily. So my cage gives the passenger something to hold on to on entry or exit. I plan to put a sign on the cage at that point telling them to "GRAB HERE".
You have about three options cocerning roll bars and/or cages.
1. Go for a cage during the build process. It is near impossible to put one in with the spider in place. Trust me I found out how hard.
2. Go for just a roll bar in the engine compartment with either a 2 point or 4 point setup. It can be put in anytime after the build and would be a better chooice as everything is in its place and the bars can be placed where ever they need to be, or things may need a slight rearrangement to fit.
3. Check with KIRK RACING at
info@KirkRacing.com. They build cages for built cars that bolt in place, allowing you to remove it if you don't want it for daily driving. There may be others that do this. Kirk's cages are certified by all the racing associations I believe. They can tell you more than I can. They are located in Mount Olive Alabama. Phone-205-608-1156. They had a display at Road Atlanta during one of the Nasa events. I met one of the owners Mark Stewart. He said his could be put into a 40. I already had mine in by that time or I would have seriously considered his. There are others who have opted for front to rear pieces that intrude in the door way. I am sure they are strong, but at my age I don't like to contort more than I need to just to get in or out. If I had a bad experience at the track, it would take me 4X as long to get out.
With mine the only consideration is that the dash will need to be altered for the cage to fit out of the door way in front. I altered mine as you can see in the photos. The piece cut off the dash will be supported by a bolt and a piece of strap that is hidden in the dash cover(there was enough padding to hide the head of the bolt). I plan to cover the dash in leather and all that should show is a seam where the two pieces come together. The hardest part was making the template for the cut. It wasn't round or straight. Wanted to make it right with the first cut and not have to take more out. I was fortunate in that my car came with a RHD setup and I ordered a LHD dash, so I had a spare to experiment with.
Bill