" no matter how tight I tighten them, they won't seal"
That's the problem. They don't need to be that tight. Here is the cheapest solution, and it works flawlessly everytime, for years to come. Go to the parts store, and buy some good collector gaskets, 2 sets (4 gaskets) I prefer the fel pro blue gaskets if you can find them. Then go to your local exhaust shop, and buy an extra set of flanges. All ya gotta do is sandwich the extra flange between the two gaskets, and viola!!! No more leaks. Please submit $1 to my paypal account for this info!!!
BTW, here is a pic.
