After almost a week of driving with it, the vehicle really accelerates more smoothly, and between gear transitions there is a smoother power delivery. There is definitely a midrange smoothness. It pulls well through the gears at lower speeds unlike before. It feels easier to leave in a higher gear at low speeds like below 50 and easy to accelerate with or without having to change gears and going up hills. Freeway it feels good, even though I hate driving the freeway most of the time. Still need to get the right mounting bolts for the header to s-pipe connection. The bolts I have rigged in there now haven't worked loose, but I think there is a very slight leak, that is really only audible at start up, but that may just the headers needing to warm up. I was able to grind the doughnut ring with my dremel to make it fit better, but I think it is still the wrong ring, the outside diameter seems way to thick, which is what is making the s-pipe not able to connect all the way properly, but even it fits properly, using the factory spring seems like won't work. I found a different set from a junkyard, but haven't had a chance to test fit them. Anyways I have no CEL and I wonder if when smog test season rolls around in just short of 2 years, I'll be able to just put the factory manifold back on and jump into the smog check station and pass.