when welding your exchaust the lower the better.even if u sleeve the bad bad parts remember what looks good on the outside is eroding from from within!like the man says,try test pipe...if you can do that then on our exchaust reduce it because its still rotton inside,simple tack welds,let it cool....
really can nobody weld on you tube?ill upload a video soon.everything from 0.3mm to 50mm gauge,how to fill gaps and how to rework bad welds with welds