Slanted mufflers will let you take a bend out the exhaust. You won't see that much of a difference.

As for ground clearance it f**king sucks. I have one on my hatch. It's a custom system with a magnaflow muffler (canister, 7" around, 4" inch tip). I had them angle/slant it to my liking but the ground clearance is sh!t. I've hit it a few times but I don't mind, it looks wicked. Pics soon.