No EFI controller required with any mufflers! They do not gain over stock, but they do not lose horsepower like so many others do. Simply a great weight savings and make it sound like there is something under the hood.
No muffler should not be causing the octane light. They have the same airflow as stock so nothing should change except your sled being lighter! I would look at fuel quality, we see such poor fuel now days it is crazy.