DC muffler seems like next best option to the CSG touring if you want a less expensive alternative.
I am very sensitive to drone, tried a bunch of different setups and many would give me headaches and ear pain, but this setup does not. Full 2.5" system, CSG CBE is technically larger. Briefly reverted to the stock FP and setup is even more tame in cabin. Wanted the FP to add a bit extra.
JDL4-2-1 EL
2.5" OP
Ultra quiet Catted resonated FP
CSG touring