Hello Trapper I used your method but left the end plates off ,I think it sounds better , a deeper sound compared to the flatter sound with the plates hiding the holes , this is a good mod and cost me bugger all and am well pleased with the sound !
I take it the baffles are removable after drilling out the rivets.. what are the options for taking them out, modifying and then re-rivetting? I would like to free up just a little more noise.
I took the rivets out of the rear ends of my exhausts but found that they only held on the ss / chrome end plate, could not be bothered to take off the exhaust to see if I could get the baffles out from the other end so I drilled 6 No. 1/2" holes (2 between each rivet following round in the same circular shape) in each exhaust and replaced the end plate with ss self tappers into the rivet holes, I used small washers to keep the end plate 10mm off the exhaust. You can't see the holes I have drilled unless you look closely. This doesn't make it the noisiest of exhausts but I am more than happy with the sound it gives out. When I take it for the MOT I will remove the washers so the end plate will cover / seal the holes and put them back on after.
I havn't found any difference in the performance of the bike in any way, all I have noticed is that when warm she idles ever so slightly faster, probably due to the lesser amount of back pressure.
Please check with whoever you think fit if you are going to try this. It has worked for me but would not wan't you to have problems of any sort. Perhaps some of the other members may have comments to make?