early A body exhaust EXPERTS!

Some say it's a measurement, others say place it for convenience, the most creative answer I've heard is painting the exhaust white, taking it for a spirited run, then putting the h-pipe where the paint that hasn't burned off begins.

I'd say put it for convenience, there is only so much room as an option under there. The fact that it's there is more important than exacting placement.

Aloha!