I have a 2000 Ultra with fuel injection. If I install aftermarket mufflers to make the exhaust sound better ( I assume they have less baffles, back pressure?) does the engine need retuned or recalibrated to run properly?
Is it possible to core-out the stock mufflers?

 

from what I have found out from lots of research,,,if you change out the mufflers and don't go bigger that 2" baffle,,you don't need to do anything,,,BUT! if you add a high flow air filter,,or larger baffle you will need to do some kind of fuel managment,,,

 

Ditto. What seph10 said.