Will the lip interfere with the trunk seal when I close the lid?

No. The low-profile design sits at the bumper level and does not extend into the trunk panel area. Your existing trunk seal closes normally with no interference.

Can I install this without drilling into the bumper?

Yes. This lip uses the factory mounting points already present on your stock bumper, so you avoid drilling. Verify that your bumper's factory holes align with the lip's mounting tabs before final assembly.

Does the lip stay stable at highway speeds?

Yes. Once bolted to the factory attachment points, the lip is rigidly fixed. The low-profile design minimizes wind loading, so it will not flex or rattle during normal highway driving.