Here's something I learned in doing my 3" exhaust.. If you can source some mandral bent 90* or a "J" pipe, get a pipe cutter from princess auto:
You can cut any amount of the curve to get any angle you want. For instance, if you just need a 25 degree bend, you cut off, say, two inches of the 90* curve which would give you the 25 degree angle.
I did my exhaust while on jackstands by eye-balling the amount to cut, tack it in place with three welds and repeat.
Now, I used mild, not stainless, so cutting stainless with the above cutter might not be an option. Once completed, I painted the whole exhaust in VHT high heat paint: it's held up perfectly though rarely sees rain.
One more thing: I used 3" header flanges to create removable sections. They're super cheap, like $10 for a pair, and the gaskets are available everywhere.. even Canadian Tire lol. I've reused the gaskets everytime, never tore one!