running a muffler
 

So I have been wondering about a muffler for my lighting sprint was looking at an after market short muffler. Someone asked if there was a rule on running one if not than why not just run it as a open header. So here is the ?

Open header or muffler and a why if possible thanks

I have ran both with and without I couldn't tell any difference.
I went back to using a muffler because it was easier on my ears.

Ok thanks I didn't know if it was a back pressure thing or not I haven't seen any rules on it