Here is what I did to my stockers. The sound is GREAT!
Went on a good 200 miler today to try the new pipes,
What I did was drill the front end baffle plate with five 1/2" holes each and then after removing the rear end beauty caps, drilled nine 1/2" holes in the rear baffle plate, three each between the screw posts. Masked and painted the ends with 1500 degree paint and reinstalled the screws. Doesn't look bad at all either.
The only possible performance difference I (think) I felt was a reduced back pressure feeling on hard decel at high revs. If I did in fact feel some difference, I like it. Not the usual lurch forward when down shifting like the very restrictive stockers seemed to do. Acceleration was not effected. Looooove the sound, really. Would like to hear it from another's perspective and not just from the seat but I really do like it. No pops or swooshie sound, just a nice deep throaty rumble.
I think if you can find a set of take offs in good condition or using your own, you can have a great sounding set of pipes for a fraction of the cost of any 'store bought' slip ons. I'd love to hear some others in a side by side comparo to see what differences in sound there actually is. Not considering any HP gains or losses, just the sound.