I know that when I did mine, I could feel an improvement but not a ton. I went from around 97 at the wheels to 101 with the intake cam, then 104 with the exhaust. With a better air intake on it jumped to slightly over 107, then 110 with a better exhaust. Now with my shorty equal length header it makes 113.4 at the peak, but makes 3-5 all through the RPM range and doesn't sign off at 5700 like it did with the manifold. I think that the cams need room to breath. Also, my torque jumped a bunch with the header from 111.2 at 4250 to 119 at 4250. Instead of dropping off at 5700 it also maintains the torque past that point. Without the header I had a max of 88 at 6250. Now I have nearly 96 at the same point.
If I can just get some better ignition and fuel control I'm sure I can get over 120 to the wheels without any further hard parts. This thing has way too slow of an advance curve and way too much fuel at WOT.
As far as the cams being worth it, well, I'm not sure. The intake cam has almost exactly the same lift as the stocker with about 10 degrees more duration. The exhaust adds .020 lift and about the same 10 degrees. Basically, they match now with the same lift and approx. the same duration. It adds power, but we really need some ECU work to get it all out. They are still very mild and don't affect the idle. I'm sure they would still work great with a turbo or supercharger due to the conservative specs.