I feel you would only improve performance. Better valve events with the cam. More compression. Better breathing in and out.Thank you both for you interest and input. Please understand just because I don't always take advice does not mean I don't consider it and see how it fits for me, A little back ground may help. I bought this 03, extended cab, SXT with a 3.9 V6 and five speed. Having never owned a V 8 or automatic for my personal use, it with timeless styling four wheel disc, big wheels and tires had to give it a shot. It was not hard to spend a couple thousand on brakes, suspension, AC, alternator and drive belt parts. At that point I could not stand the sound a std V6 makes. It sounds like it is sucking, so on went the complete single 3 inch exhaust system. My exhaust guy is third generation and does the NASCAR exhaust school every few years it is made of the correct parts. For a whole year it was great and ran fine. It did not begin to show issues till I started making long high speed trips pulling 2000 lbs. The first one went fine no codes no issues. I had learned a few things about the ride. Just a wild guess but I feel it's at least 20 HP short of what I need. Just running up and down 95 even small hills are an issue in O/D 5th. Having never heard a V6 in lugging distress it scared the crap out of me. I though the engine was coming apart. OK, no towing in 5 th gear. Even in 4 th it's a little short of power. Many have suggested more rear gear which would move things up the RPM scale. With something in the 175,000 miles on the OD the engine could use a freshening up. The cost of a std rebuild using stock parts with no effort to improve is big money. So I'm spending a few more dollars looking for something that may not be there. We have a local shop that holds an open Dyno day a couple of times a year. Once done I may give it a go. As for the Keg issue I believe there is something to be had there. If not HP it may be something that supports other power adders. Again, thanks and I'm about ready to start. If I had someone to text pictures to that would post them to a thread as I add text it could be interesting to some. Steve
You have no choice but to see some nice gains in my opinion.