Don't waste your time drilling the stock exhaust.
Waste of time near as I could tell.
Hard finding a bit that long too, but besides all that,
the Triumph TORS sound better than the OEM drilled out.
If you just want loud, I've got a solution.
Get yourself a used harley slashcut drag pipe,
weld it on right under your O2 sensor hole.
You'll get LOUD.
In fact, I've got one welded onto a stock header.
Be forewarned you'll loose a lot of torque unless you put a baffle in it.
But it is loud....
Don't do the hole drill method.. I've never heard a drilled set of pipes sound worth a crap. I don't know which R3 you have, but D&D sells a set for the Rocket III Standard/Classic for around $500.00 and they bolt on in no time.
And I have witnessed my Jardines saving my life. If the driver had not heard me, I would have been a statistic instead of a witness..
Just be aware that the internals of the Rocket stock muffler are quite different to the VTX. Someone posted a cut away of the R3 muffler previously and it was clear that just drilling the back plate as was done with the VTX won't actually achieve anything. You need to go much further in. If I can find it I'll post the pics but meanwhile have a read of this thread. http://www.r3owners.net/general-tech-talk/8578-punching-out-exhaust.html?highlight=drilling