Sure he should plan for the worst but dont scare him away like it is inevitable.
Running nitrous on a 3.8 is very feasable, many people have done it with success. I planned on running nitrous on my anemic 3.8....might still do it but currently its buried under 16 other 4.6 projects. I planned on going with a hidden wet port system.
If you go with a wet system and inject the nitrous before the TB and keep it under a 75 shot. The fuel will puddle in the plenum where it takes a 180* turn back into the runners. Ideally you should set up a port system and inject the nitrous/fuel directly into the runners. You could run a bigger shot if you went this route.... A few have gone up to a 150 without problems....granted they know thier ****.
Colder plugs, larger injectors and an upgraded fuel pump should be standard.
Some supercharged cars blow.......Others just pick up and move.