Thanks for all the replies. This is what we are seeking, input both positive and negative! It helps with our decisions. The venturi effect is interesting. It seems like a header collector extension would give that effect. We felt this could be done by positioning the cutout at the classic 18" ish point past the end of the header, to give the best torque. We just felt that the compactness of this design would be the best all around way to go.
If built, we want to keep the cost reasonable so folks can try them and experiment with them. We feel that there is a market for them with those who want to win the loud exhaust competition
The peeps that want to run around for the day uncorked, The racers, both drag and road race, etc. Lastly I believe many rides that have cats, especially stock cats, can run the track insert open as the cats cut the sound down. I installed one right after the cat, on my wife's stock 2003, 4.7 litre Lexus suv (yes I know, shameful). With the track insert in driving around normally, it just sounded like an aggressive cat back. When you stomped it and got into the sweet spot it sounded really nice! Some people thought I had supercharged it.