I have been looking over my exhaust, the traxxas resonator, as well as a few others we have over here to compare to. Unfortunately I don't remember what makes but to be quite honest there are very subtle differences. I've seen nearly identical exhausts make very different sound simply because of the material the pipe was made of or it's thickness but without swapping around, couldn't really compare the power difference between them.
There are things you can do to your stock exhaust to change your performance as well. I've seen other posts where the exhaust "nipple" was ever so slightly milled out to a larger exit hole to allow faster air flow. Keep in mind, this will also reduce back pressure and may sacrifice low end torque. A careful gear adjustment may make this unoticeable and also capitalize on the top end gains. We now have 3 identical 5308 model 3.3 revos here in iraq and now I'm considering drilling my exhaust out a tad just to see if it makes any difference. Before, it was pointless, but now that i have something to compare to makes it a worthwhile experiment.