Here's my solution to an oval tube mount. Long bolts screwed into the mount with coupling nuts to tighten. No cutting required (although it would be easy to grind the heads off the boltsfor a more sanitary look)
Here's a better view of the latest pipe
Has a nice sound and good torque, with a nice sweet spot right at my normal cruising speed. I also run a 41 tooth sprocket to drop rpm's a bit.
If more is better, then too much is just enough.
If you can't afford it, build it yourself.