Somehow I missed this thread when it popped up several months ago... I would have loved to contribute to the conversation. Better late than never.
When you start talking 180 degree headers, the dialog can become scientific in a hurry. Rather than diving into the science, lets talk about putting them into a V8 Fiero.
The bottom line: it's all for the sound and great low-end torque for the street.
Fieroguru played with this idea years ago, I simply continued with the concept. I am an experienced welder, but even I admit that I'm not up to the task of building 180's from scratch. I admire anyone who has the skill, tools, time and patience to build them.
After a lot of measuring and eyeballing, I came to the conclusion that the Schoenfeld 179-2's would fit with some tweaking on the Fiero... which is much easier than building these headers from scratch. That said, I don't recommend them for anyone who doesn't have some basic fabrication skills and tools. But it's more than doable if you don't mind cutting into your beloved Fiero... like me.

I am currently working out the post-collector exhaust system details. So far, I am pretty well convinced the a 2 into 1 system is going to be ideal for weight and performance considerations, but also for the ultra-wicked sound it will produce.
Radiant heat is always an issue with 180 headers, so heat insulation with be used extensively in the engine bay, deck lid and firewall accordingly. Combined with ceramic coating, fabricated heat shields and proper air circulation, this system will work just fine in the Fiero.
Questions and comments welcome... in my build thread, I tried to explain the basic steps I took to get them to fit. Up next I will be fabbing the rest of the exhaust system for a true "exotic" sound and look.
[This message has been edited by ITALGT (edited 06-18-2015).]