I have sewn many, many t-shirts using twin needles. Yes, I have come up with my own solutions to the tunneling problem. The September 2010 issue of Threads has an article called "Flat Feet". Talk about a light bulb going off. It seems that using a foot with the flat foot instead of a foot with an indention will help with the tunnelling problems. I need to play with this idea. It could be that I was was using this type of foot without thinking about it. Just a basic zigzag foot.