Hi all, does any body know if additional support is required when chopping a t-top to convert to a cabriolet?, I am thinking of doing this mod, I have a 1983 firebird daytona anniversary edition, would doing this mod hurt the cars value?, would changing the car colour hurt its value, I've had to restore the car as it was in pieces when I brought it, the body was in a bad state which is needing a full paint job, car is currently in primer, so I thought I'd best ask these questions now beforehand, I reside in the UK, does this effect value, thanks for any assistance

<sarcasm>The best mod you can do to this poor car is douse it with petrol and set it ablaze.

No. The mod I suggest won't hurt the car's value. Should increase it.</sarcasm>

By Cabriolet, do you mean full convertible, or just remove the bar in between the t-tops and perhaps use a canvas top with snaps, or something similar?

The answer is yes, IMO. You would have to reinforce the body similarly to what ASC did to the convertibles from 87 to 92. That "bar" is definitely a structural member. I cannot tell you exactly what they did on my 91 TA Convertible, but there is definitely additional structure in there.

I would also add subframe onnectors.

We called it a targa top here stateside. It was a thing for a while, but people figured out how much worse it made their cars and stopped.
unless the car was designed for it, I wouldn't consider it at all unless you're going to add serious structural enhancements.
it'll be like driving a overcooked wet noodle