The most important thing is
You've got a van that weighs 4000lbs that has a tiny diesel that makes 80HP in good condition
(Though my Exceed weighs closer to 4800lb). It's never going to be fast, and the gearing means you're never going to cruise comfortably or economically at 75mph.
The 4D56 is tuned to be slow and reliable, and suit Japanese traffic and speed limits. Before you start trying to make it faster, you'll need a boost gauge and an Exhaust Gas Temperature gauge so you don't end up blowing it up.
The first thing is to fit new air and fuel filters, check your valve clearances, change the oil (every 5000km), and replace any ancient coolant hoses. You might be surprised at the difference a new air filter makes if your old filter is clogged. The rest is just so you don't cook the engine later.
Opening up the exhaust/fitting a side exit makes a noticeable difference, even without any other changes, and is worth doing before tuning the engine.
Deleting the EGR won't make any more power (unless it's malfunctioning) but it will help prevent crud buildup in the head.
A snorkel doesn't do anything for power- the air intake comes from in front of the radiator already, it gets plenty of nice cold air.
Once your engine is prepared to make more power without asploding, here's the post about
tuning the 4D56 for more power.
