7 psi is safe to boost on a stock d-series motor
I'm currently driving a midroof VNL780 with a 233 inch wheelbase. It's a heavy one - roughly 18,000 lbs. However, it has the larger D16 motor, plus a headache rack laden with chains, binders, and other flatbed equipment.
Stock engine 127hp
$110k - $150k, depending on options. Whatever you do, DO NOT get the D16 engine.
FH is a larger cab, and, IIRC, can be had with the D16 engine.
non-vtec d16 engines have about 106 horsepower
you need a special tap, puller and install tool. Buy them or get a dealer to do it.
64 - D16, D16
105 - T20, 13, D16
The VE D 12 has a pretty good outlook, and is often cited for its efficiency. Being only a 12 litre motor, it doesn't have the power of, say, the Caterpillar C15 or the Cummins ISX, but it's lighter, and still gets the job done. The VE D 16, on the other hand, has proven to be a very powerful, but ultimately very problematic motor. I ran a Volvo VNL730 with a 565 hp D16.. thing's a powerhouse, but plagued with issues.
The Volvo D16 engine outside of the North American market is available with up to 750 horsepower.
124 - T20, D16, D16