Can you come up with a similar idea but for motorcycles? Have it simulate that open pipe sound that they love, pipe it straight at their faces so that they can enjoy it--and leave peace&quiet for the rest of us.
2011 Toyota Camry, base, 2.5L/6MT, 200k, hers
2010 Toyota Tundra DC, 4.6L/6AT, 157k, ours
1999 Toyota Camry LE, 2.2L/4AT, 221k, his