I also only use titanium coated topstitch needles for all my sewing. I learned through trial and error that the good stuff is good stuff.
I use Connecting Threads 50 3 ply wt thread a lot (great colors) and use a size 90/14 needle with a size 60 or 70 wt. thread in the bobbin. I start with 0 tension and go up 1/2 at a time until the stitch is what I want.