Everyone stop and re-read RJs post. Don't adjust the timing or change injectors, adjust your thinking and change your expectations...
With all due respect, Stolaas can change the injectors and change the cam timing, and it will increase the horsepower of the engine which will improve the performance of his bus. "What kind of injectors would you go for and what would be the cost for them plus installation?" After all, he did ask the question!
I did all of the above. And there was a very noticeable and tangible improvement in the performance of my bus.