Well, realize that the baffles are to prevent water intrusion and that there are also resonating chambers tuned to particular frequencies to produce a harmonic resonance boost to the intake charge at particular rpms. This is why almost all after market tuner intakes do little or usually impede engine performance. The VH45DE in particular is free breathing and exhausting with low restriction true dual exhausts. Total power loss vs. open system is about 3%, tough to improve upon without a major comprise of intake filtering or exahust noise and vibration.
Just be real careful with your tires, and personally I wouldn't go over 80 mph, especially in summer. You probably do have legal recourse to the shop and probabably some leverage with them for installing such under specification tires.