I have a 97 f150 w/ 4.6l, 4x4, s/c, 3.55:1, tow package with 125k miles. I tow a 18' boat w/ trailer (approx total weight 2300#) almost every weekend. The geography in which I live in is almost all hills. The engine has been great, but I would like to add some additional hp and torque. I already have a k&n air filter in it. I am considering buying a exhaust system (flowmaster or gibson not sure what would perform and sound better). Is there anything else that would all would recommend? Thanks for your input.
If you tow that often, the most logical idea would be to get lower gearing. You can add all the horsepower you want, but if the engine still has to struggle to turn a ratio too tall (3:55 is NOT optimum for towing), youre not really fighting the problem at the base. Id suggest dropping down to 4.10's.
The 4.6 is not a good engine choice to begin with for a 4x4 supercab truck that weighs just over 5000k. The 3.55 axle is also inappropriate for towing. However, some aftermarket headers and a high flow exhaust will wake up your engine abit. I put JBA headers in mine a few years back and they are expensive, but they add about 20 horsepower. Check out the JC Whitney catalog online and you can find some low cost alternatives by Pacesetter. They have basic black, the cheapest, and for an extra hundred bucks they have stainless steel shorty headers that look really nice in the pictures.
Just my opinion but.... Pacesetter may be cheap but the product is not worth what you pay. After dealing with many of their products I had troubles with poor fittament, leaks, corrosion, shoddy quality, etc. I would recommend choosing another brand or at least buying Pacesetter from somewhere that will let you return it.