Been there before on the closed tank valve before :lol
Nothing really wrong with stamped collectors, they are just general pieces without any parameters really taken into account. A fabricated collector with a tuned spigot length, convergence angles, and a tuned mega phone are where you’ll make the power.
again though, not bad for a budget header 
KrazyKid…backpurging is just as it sounds, purging the nitrogen/o2 from the primaries and filling with shielding gas(argon, helium, xenon, etc). If you cannot back purge the part you can use a flux(I like Solar Flux type B)
Most stuff like this I just put into my welding chamber and fill with argon or helium(for titanium) as it ensures a complete purge.
----> Adam(boxersix) on JVG's computer<----.