What is the cheapest way to increase the HP on my infiniti qx4

Make sure the floor mat is not stuck under the gas pedal, thus preventing the gas pedal from being floored.

exaust.
fuel filter(new one)
intank..lol l lie

Sell that one and get a 2001-2004

Going Down Hill. Let the gravity give you a boost. Cost nothing and always is there to help you.

:-))

JATO rocket.

add a turbo for 2grand. upgrades that are $300 ish will gain only like 15 hp, if u want something like 120hp gain get a turbo..