2005 Stock Exhaust- Ultra

Hi Mike;
I have a 2005 Ultra with the stock puny mufflers on it, a friend of mine, drilled out the mufflers for me the bike runs good, the sound is ok, My Question is do I need to put on a screaming Eagle air filter and have the EFI remapped? Gas mileage is still at 47 and power seems adequate.

[Mike]

If your are looking for more performance, the air cleaner kit along with the exhaust mod will give a good bang for buck. It's the air in-air out thing, in order to make more power we need to process more air. An open exh. will allow more air to escape but if more is not allowed to enter (air cleaner kit) then the performance gains will not be realized.
To answer your question, yes you should either recalibrate or remap the injection. If we've added air we need to add fuel to maintain correct air fuel ratios. The bike may be running fine but a properly mapped may run much better. For the mods that you've done, a stage download may be fine. If you are planning future changes then Race Tuner would better adapt to those changes. Gas milage may suffer but should still be 40-44mpg.
Regards, Mike