DJ Dep
refugee from the other place
I think when you weld the tube into the collector it's supposed to stick down 1/4"
Doing some searching it seems that it's worth at least 20 hp according to their claims
The instructions do show it inside the collector, but I don't think that's mandatory. Bird is right....putting it inside the collector would restrict airflow and cause turbulence. Probably taking the "tune" out of the exhaust. Seriously, I don't think it's necessary to sink it inside the header. The passing air from the exhaust will suck the vapers out of the hose quite easily.