You'll be okay with the 60mm exhaust. It won't be the end of the world.
If you do decide to do a new exhaust, I would go all the way to 3 inch for sure.
If you want to make it quiet, you need to spend the money on the proper resonators and muffler.
If you do decide to do a new exhaust, I would go all the way to 3 inch for sure.
If you want to make it quiet, you need to spend the money on the proper resonators and muffler.