Got to drive the truck, finally! Here's what I think so far:
The performance side of things is great. There is a distict improvement over what I had. It feels strong thuout the entire RPM range, and exspecially the MID to High RPM range. The truck pulls good and really good in the high RPM'S. There is no loss in lowend at all. Actually, it feels stronger there as well. I love the performance and If your looking for EVERY thing you can get from your 4.0 SOHC then headers are worth it. However, if you plan to buy a set of JBA headers, I would buy the Steel chrome plated version. If you didn't know, I went with the stainless titanium coated headers. There great but I'm not sure the extra dollars you pay for them are really worth it.
Now, the bad part. I'm not really fond of the sound I'm hearing when at WOT. It almost sounds like a supped up motor boat? Hmmmm, I may get use to it, or a my change the muffler again? Anyways, all and all, i'm pleased with the results. Now, I'm curious to see the numbers from a dyno.