Hey David - great to see you in the forums. I'm not sure I expect so much from those two components themselves. Five to ten hp would be nice from each. Personally, I'm more interested in how they work in conjunction with other upgrades (meaning higher hp levels). Of course, I may not be the majority though.
I think there's two types of enthusiasts - those who want to upgrade only their exhaust system for a little extra power. And those who would install headers - which means they'll probably do a whole lot more to the car in order to achieve big power gains. I would think you would want a couple different systems to target both goals.