With the bolts removed, pull off your fender and you'll be ready to install the cowl brace. Before loosening any door bolts, if your door is well aligned, tape it in place to keep it from moving. Of note for Miata owners that keep their SRS system, the wiring within the blue loom will have to squeeze through the small, semi-circle cut out of the V8 Roadster's brace. As I had already un-safed the car a few years back when removing the airbag, I took this opportunity to pull the wire harness out completely.
One trick that may help when installing the cowl braces is to tape up the door seam to keep it from moving when you loosen the door mounting bolts. We found some surface rust hiding on the car under the fender, so we tackled cleaning that up and then we found ourselves in a bit of a tough spot. For you, our loyal readers, we really tried to determine the added chassis rigidity the cowl braces gave us and used all sorts of methods to measure the difference in a repeatable way. I would later learn that torsional rigidity is a very difficult beast to calculate without some sort of chassis rig and that even the small measured changes can translate into large improvements. I should have been using dial indicators, not measuring tape and scales. I took weeks of my time trying to measure and come up with different methods, but I failed you. Please have mercy on me and the next time you see me, shake my hand and say, “you suck, but at least you tried.”
Before we installed our new braces, we took the opportunity to put them on the scale. Both sides combined, hardware included, came in right at 6 pounds.
Installation of the brace is fairly straightforward. Loosen and remove the two lower door bolts completely, just one of the top bolts, then loosely install the brace into position. From there you'll want to install all of the hardware finger tight, then tighten up everything a little bit at a time to reduce the chances for stress or side loading any of the hardware.