Quite honestly, anytime you allow a motor to breathe better, the motor will work more efficiently. Whether or not we are adding bottom end HP or Torque or whether or not it's at the top of the RPM curve, the fact of the matter the motor will work slightly cooler, and gas mileage on highway should be slightly better. Those things coupled with the fun sounds like a plenty fine reason to do these types of modifications, and if a motor works more efficiently, then towing is less of a stress then before even if it is slight. To say you see no increase in performance with intake and exhaust mods is on the exteme side as well. A combustion motor is a vacuum sweeper, it sucks air through an intake into a combustion chamber, mixes with fuel, detonates and pushes gases through the exhaust, relieving the restriction on either sides of the equation (EG- intake,super charger, turbo, large diameter injectors, headers, high flow cats, and high flow cat back systems) will only increase performance. When I say increase performance, that does not equate to dyno stats, that may just make a throttle more responsive, might mean 2 or 3 miles to the tank more, or if you went with the big mods, a whole lot of HP/Torque. It may also have allot to do with altitude, if a person lived in a higher altitude situation, an intake could make a big difference to the individual by allowing more of the thinner air into the intake.
My 2 cents, I know there are plenty of very knowledgable folks here, so if I am wrong, please feel free to correct me. I just want to make sure someone who wanted to spend 250.00 on an intake realizes both sides of the fence, You will not make 50 horsepower from 0-60 by adding one, you may add up to 3 miles to gallon if you keep you foot out of it, but it alone is not a miracle box. Not to mention the stock intake from Nissan is a very good unit!