It's important to know the weight and ply and content of thread then you have to select the needle size and type of needle for that thread. I use 2 ply 50wt or use a 60wt or higher for piecing. The thinner the bobbin thread the better. I don't try to match my bobbin thread to the top thread in wt. or brand. Doesn't make a difference to me. I use titanium coated topstitch needles. It's easy to find the wt and ply info for thread by going to the website of the thread if it isn't on the spool. Right now I'm using Aurifil for the top (because I have a lot of it) and prewound Sew Fine bobbins from Superior Thread with a size 80 topstitch needle.