I believe that "dead leg muffler" is to help muffle the sound more. If you notice, the main canister type mufflers are smaller than some of the other exhausts out there. I believe they designed this with clearance in mind.
If you look at the FI mufflers, they're much bigger and therefore, you have more of a clearance problem. Now, I can't say how severe the clearance is with the FI....whether or not it effects you as a daily driver but it's substantially lower than stock....and ARK's, I assume. Of course, one's ride height plays a factor in this as well.
But.....I could be wrong. So hopefully someone from ARK can better answer your question.
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