I was looking at the tools I currently own and wondering what I can do to make it just a smidgen louder. I have some long carbide drill bits and was thinking about just punching four 3/8" holes in the end plate of the baffle. Any thoughts on why I shouldn't do this? Seems a less aggressive than cutting out the endcap like 04ctd's approach.

 

I cut the the end pipe out of my exhaust pipe using a 42mm hole saw . You dont have to remove the pipes. It sounds a "little" Throatier and louder, but if you guys are looking for "loud" this isn't going to be enough. I removed mine because I wanted a less restrictive exhaust system ,with out paying $600 for slip on"s,

 

doing small holes won't make a difference, doing my way barely made much difference. you should pay the ~$40 for the hole saw, so you can do your buddies bikes.
it's worth it

this is true, there are many posts about the M8 being too quiet.
it's physics: if you have a crossover or 2-1-2 it makes any thing quieter (cars, bikes) but if you run true duals, it makes it loud.
so it appears the 4 valve head is doing the same thing: making the exhaust pulses quieter.

IDK if this small mod helps, but the OEM setup is too quiet to keep cages from merging over on your bike, so I think this small mod is a good start,and it should be warranty friendly, so that makes it a no-brainer, esp if it helps the air flow thru the CAT and minimize heat from the CAT on your leg.

 

video of the M8 Vance & Hines Power Duals with OEM slip on mufflers:

 

But I must be honest with you and say that you want to do it cold because it leaves some nasty blisters...

 

Finding after market anything is tough especially for the M8 107 but the Cobra slip-ons will work just fine till I get her in the shop for a whole new exhaust and intake. I am really surprised how nice the Cobra's sound. They sound like the big-boy Harley it is when hittin the gas or cruising at 65 on the highway yet won't wake the entire neighborhood at 6:30 am (unless I want to hehehehe)