To Muffle or not to Muffle......

Anyone have any info about drilling the standard mufflers to make 'em louder? (I got a spare set of standards to 'practice' on)

I looked on the old intermaweb and i've found a couple of sites saying that you can drill through the first two baffles in the standard exhaust, to make 'em louder...... but i also found stuff saying that if you do, you need to alter the fuel mixture settings else it'll be running to lean.
But then i found someone else saying that the ecu will automatically sort itself..... confused!

[sullspots]

I drilled the baffles on my 2011 sportster.I had trouble finding a drill bit long enough,it has to be 8 or 9 inches to reach the baffle plate.

I drilled a pilot hole with a 10mm drill and then used a 20mm drill to do the final hole.The result is a much deeper sound but not too loud.

I didn't do anything with the ECU as I'd also heard that it will automatically adjust the mixture and the bike seems to run OK.I was going to do the "Gronk mod" but it seemed like a lot of effort especially on silencers with a cat.

Gronk mod???

I've now discovered that the 'spare' set of mufflers (off my 2010 streetglide) are smaller than my new ones (was 3.5" now 4") so cant practice, also ive had a look and one side (LHS) has the 'plate' piece of metal i was expecting but the RHS has an already semi opened part that I can see.... do i drill this to open it more?

Still confused lol