Pretty certain it's coming from the engine compartment. My exhaust run all the way out to the back and the odor is not quite like exhaust. Standing back by my exhaust with the car running I don't smell anything like this particular acrid odor (best I can describe it - not overpowering but definitely something noticeable at times.
Not sure what I would have to do for PVC. My carbs do have a fitting (not sure of size) but since my primary carb is up front I would have to study the access to it.
Things are pretty tight.
