Although anyone at the last couple Run For The Hills will attest, I do not hesitate to push our convertible to the limits in the twisties. However, it is certainly not as stiff as a coupe. I do get a bit of cowl shake on rough roads (Michigan was hell for this car...but I rarely notice it down here). This is a duke/auto, which is famous for excessive vibration at idle in gear...and I can definitely see some movement in the windshield frame during that vibration. I don't notice that movement while driving. Although the doors are pinched a little, this has not gotten worse through the years, and is not noticeably worse when Sharon and I are in the car (neither of us are a lightweight). The doors are not original to the car, the quarter panels are original Mechum scoops that were installed poorly, and the upper panel behind the door was custom fiberglassed. I think we can resolve the pinching by re-aligning the doors and correcting the rear when we re-paint.
The top is built like a tent with poles that hold the top up and the fabric snaps into place. This allows us to completely remove it, and fold it up into the front or the trunk. It has a nice smooth look when the top is off that I think is far superior to any of the normal convertible kits. But...when the top is up, it has a goofy shape that cuts off square at the back...and it leaks. Bad. I normally tell people that I don't know if I get wetter with the top on or off in the rain...but at least with the top off I know where the water is coming from.
We purchased the car as a convertible in 2010. It was converted in 1997 by Denny Patton. We have put about 35k miles on it (it now has 265k), and have driven it to 12 states. I do love driving the convertible when the weather is nice, and don't regret getting the car. It gets lots of attention at Fiero gatherings...but outside of Fiero people, few notice that it is anything special. It definitely has it's drawbacks...mainly in foul weather.
These are some pics I took in the fall to show someone how the support is on ours.
From just in front of the front tire, you can see how it is welded to the front crossmember. Not sure I like that, makes future repairs more difficult.
Same location, different angle.
From behind the front tire looking forward. Note the conduit with battery cables for the front mount battery.
Same position, different angle again. Notice that the support does NOT block the gas tank.
In front of the rear tire. You can see where it runs up the firewall, and has the crossmember behind the gas tank. Battery cables are also visible again.
The support runs up the firewall, and out along the B pillars. The seatbelt in this pic is bolted to the added support in the B pillar area. I am only 5'9", and am the tallest person that is normally in the car. I would recommend a higher shoulder mount for a taller person...but most convertibles I see mount it to the firewall, which plays hell on the seatbelt retracting.
If I were to build another one, I would do underbody support similar to what we have, along with support around the doors similar to what this guy did:
http://www.fiero.nl/forum/Forum3/HTML/000006.html#p9 I would also do a different top design. I have thought about several different designs, and will be doing one of them just before paining the car...but even then, this will be a nice weather car only.
Overall pic of the car on the way back from RFTH 18:
Pic with the top up at RFTH15: