Whoa... Don't believe everything Peter says off the top of his head...
Without special flares to enable a wider track, an under-car exhaust is not possible with anything wider than 6" (
maybe 6.5") in the rear. And then only with the Jag-based rear suspension.
I haven't modeled the ERA rear suspension into the Slabside layout yet, but the narrower track is going to make it very close. I'll check Monday or Tuesday if things aren't too crazy. Under-car pipes all the way to the rear is definitely out of the question.
In the front, I strongly doubt that the (7.5" wide) wheel offset can be changed enough to fit without flares and widening the track.