Ive also been working on the exhaust headers, which has been a real PITA.
Keeping all the tubes the same length and having to fit them in the confined space of the Fiero engine compartment (especially the rear side of the engine where it sits against the trunk wall) has been a challenge. I had to temporarily mount the engine to the 4T60 trans to make sure I was staying clear of that as well. The rear of the engine piping is done now, I just have to finish welding up all the seams. I couldnt imagine trying to do this with the engine in the car, there would be no room to work at all. The front of the engine should be a lot easier, since I have over twice the room between the engine and the cabin firewall to fit additional piping.
The header is a stepped design, starting out at each cylinder with 1.5" tubing. After 18" from the valve, it steps up to 1.625" and then travels another 18" to a 3 into 1 full merge connector. It then steps up to 1.75" and goes another 18" to a Y pipe, where it meets up with the piping from the other side of the engine. The 1.75" piping coming off the Y connector travels all the way to the rear of the car, where it megaphones up to 2.5" in the last 1 foot of piping.