What is the ruling on equipping a car engine with "headers" to increase its power, and what is the ruling on assisting others in doing so, taking into consideration the multiple uses of such an enhancement?

Increasing the power of car engines carries two detriments: reprehensible extravagance and the dangers of speed to lives and property. Extravagance is forbidden by Sharia, and the wasteful are brothers of devils, and Allah does not love the extravagant. Excessive speed causes an increase in car accidents. Therefore, the ruling on increasing engine power—beyond the usual—oscillates between reprehensibility (karahah) and prohibition (tahreem). This includes increasing power for competitions, hunting, or adornment, all of which constitute squandering of wealth and endangering oneself. Some scholars may view extravagance as prohibited, not merely reprehensible.