I think some people call it lobster welds. I like this method because stainless u-bends are really expensive, so this way you can save money on the material. Another factor is if you fab it right you can keep the true inside diameter for higher flow. Only down side is it takes more time for fabrication.
how do they look dirty tig'd ?? thats the cleanest method of welding.. cut and weld is an amazing solution to space and shape. your posibilitys are endless with this method. but it is a hard method to do correctly. most people just cut there pieces at a constant 15degree angle whic is for me the max angle to cut at. the way to get smooth segmented pieces that flow together like martin did for the cobra dp is to have variable degrees to get them to make a smooth non turbulant bend. either way this is the method i use on my cars.