Will this interfere with my front bumper or undercarriage at speed?

The 3DS profile sits low but does not extend beyond the factory bumper line. Verify ground clearance on your specific setup before install — driveway approach angles and suspension height matter. If you run lowered suspension, test fit and check clearance on your first run.

Should I seal the carbon fiber, or will the twill weave hold up to moisture and road salt?

Hand-laid carbon fiber without a protective topcoat will absorb moisture and oxidize over time, especially in salt environments. A clear coat applied before installation preserves the weave, prevents water ingress, and protects against UV degradation. Sand and prep the surface, then apply your chosen automotive clear coat.

What's the best way to mount this — adhesive or drill-through fasteners?

Both methods work; adhesive keeps the front end clean visually, while fasteners offer easier removal down the road. If you choose adhesive, clean the factory bumper mounting surface thoroughly and use a flexible automotive-grade adhesive rated for carbon fiber. For fasteners, reference your vehicle's service manual for hole locations and torque specs.