I read over on Pennock's that a guy used the exhaust manifolds from a 200? Camaro with 3.8 in it and turned them around on his 3.8 in a Fiero. Apparently, the manifolds turned around make it sound more like a 2.8 Fiero rather than the burping sound of the 3.8 with stock manifolds. The length of the exhaust runners changes the sound compared to stock 3.8 FWD manifolds.
You could then set up the rest of the exhaust like Lambobuilder showed over on MM and get a pretty nice sound from the 3.8. Certainly not the European 180* sound we all strive for but much better than the oem sound.
If you are using the Fiero transaxle setup though, the front exhaust manifold comes down right where an A/C pump would go. One down side.
If you are using the longitudinal setup, you could also build in a set of headers that change up the tune/tone. In the end though, the only way to get a 180* sound is to set up the exhaust so it scavenges 180* apart the same as those engines.
Cheers
Don