It's not specific to having a chambered muffler or not, but if you're concerned about cutting the diffuser, one option is to raise the muffler so it sits wholly inside it. Then you just need a hole for the exhaust exit.
It's not specific to having a chambered muffler or not, but if you're concerned about cutting the diffuser, one option is to raise the muffler so it sits wholly inside it. Then you just need a hole for the exhaust exit.