Most people have the di after the pump however we set our systems up so the di is before the pump.. This has a few advantages.
1 - when running 2 pumps there is no interference, that is each pump and reel line is completely independant of the other.
2 - it eliminates the risk of creep stress fracturing of the di vessel (creep stress is caused by stress on a body - in this case the vessel - over a period of time.