90 F-150 4.9litre - Tow Vehicle How do I....

There is noway the K&N didn't do squat, you may not have felt 20hp or ftlb but it lets the engine breath freely which gives more hp and better gas mileage. It comes with a 1 million mile warranty, so you never have to change it, heck you don't have to clean until 50k miles. With the price of gas its well worth it, I see no good reason not to have one. A K&N is the very first mod any car I own gets. Another 'little' thing you can do is pulleys. If I had a 4.9 and wanted more power though, I'd probably do something with the head, either the stock one or a new one. If you give it a good performance tune up you might be surprised.

Oh and the tranny cooler is a great idea but if the truck came with the tow package it should already have a heavy duty trans-cooler.