Where are you guys buying your titanium filler rod, I don't want to buy a 2.5kg box and was wondering does anywhere sell smaller quantities? Also what tungsten do you use?
Just a normal tungsten will work fine, anything that works well on DC. It's shielding that's where you need to up your game, a #12 cup or bigger, generally for strength you want that weld to come out shiny silver with no oxide at all.
I bought a handful of rods off ebay to modify some R1 exhausts a few years back, not sure what I'd do if I had to buy more... possibly look for somewhere selling by the kg?