I believe that most all the kits stiffen up the car, so it comes down to personal preference on appearance. Hall's or Byers kits (basically the same as Byers used to work for Hall) are probably the most popular and I think are a bolt in (don't you have to weld them together though?). I have Larry Stocks lower cross braces that require some mounting plates welded on for the lower front. My upper rear will be my own design.
I've said before (and got flamed), I don't believe unless it's an all out racer the upper front braces offer much stiffening as the front tub area is a box section in itself.
Julian
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