Thanks to the fuel tank, there is really no other way to route the exhaust. Any good exhaust shop or custom exhaust should be mandrel bent, as opposed to crush bent. That will help considerably. I wouldn't worry too much about the bends building back pressure. The pressure coming through is so much greater than the back pressure caused by those bends that it really isn't an issue.
If you can find a better route, don't hesitate to share!
