i had holes in my exhaust manifold on a mazda 626 years back - i went in to have it replaced and a new exhaust put on and when i came back (expecting to see a bill of $500 or more) the guy told me that he welded it up in a few spots and it should be fine ($20) - he said he would have felt bad if he put all that on there when it didnt need it - it lasted another 2 years without any problems until a high school girl ran a red light and smashed me into a gas station (first time i realized i dont like airbags) and totalled it
long story short, i dont see what it could hurt trying
and he has been my go to mechanic ever since