I have a 2004 fuelly Road Glide, and I refuse to take it to the stealership, and pay some monkey to bolt on some parts that are way over priced.
Anyway, I have built my own mufflers for my vette, and 4x4 E350 ambulance. So I have some knowledge of sound reverberation in the mufflers, and besides I like to experiment, to achieve different sounds.
I have drilled four 1/2" holes in the inner baffles of both mufflers, and two 1/2" holes on the outer baffle. The sound at idle is great, I may experiment a little more with the cruising sound I would like. Maybe weld up some of the holes, and drill a larger one in another location, to achieve a deeper sound. I know it is not recommended to modify the stock mufflers without a remap. Will this cause any damage to the engine? And would a Power commander, or other self tuner be of help to me?
Everyone I talk to, has no remap for modified mufflers, and no recommendations.

 

In my 2005 RKC stock mufflers, there were two center plugs that I drilled out - one about half way down into the muffler and the other about 6 to 8 inches from the back. The sound is pretty good and overall happy with it. I ran them for a couple hundred miles, pulled a plug out and took it to my mechanic and he said it looked good - not too lean.

I will eventually put on a set of V&H (headers & mufflers) or Rineharts true duals, with a arlen ness big sucker and a TFI tuner. All said and done about $1,000.00 and that is buying the pipes on ebay. So the current modified mufflers will suffice for now.

 

I'm thinking of drilling or trying to knock out the baffle plugs.I also plan to put a better air box and I expect I will need to re-map.It's been a couple months since your post.I,m curious to find out what you came up with. Please reply Curt (proud owner of a 05flhrsi,2200 miles riden in my first month}

 

It's easy, just use a hole saw

 

I ride an '03 Heritage Classic (EFI). 1st thing I did when I got it home 2 years ago was drill a few holes in the baffle weld and then use my dremel tool to cut the rest of the weld out. Removed the entire baffle. I've been running it that way ever since. Sounds great. Gas mileage is around 45 per gallon. Throttle response at all ranges is superb. No problems at all. I'm told that the EFI computer compensates for the change in backflow. I'm looking at changing to the V&H Long Shots and maybe adding the V&H FuelPak or the Dyna Power Commander.

 

AZ, I am running V&H Big Shots Staggereds on my '03 Heritage Softail, and my Harley Dealer could never get the mapping right. So I recently installed a V&H FuelPak, and it works as advertised. I had to play around with one of the settings to eliminate decel popping, but I finally got it right.

But tomorrow I need to change all the settings (easy to do) because I just installed quite baffles.