It's not "just poke a hole in it"... it's a little more than that.
Below are two exampes of "modified" stock exhausts...first is my stock C5Z06's mufflers(which are Titanium) and the second is a Porsche 996TT's...
In the Porsche 996TT world, a similar exhaust modification was done...but it entailed inserting a torch or router bit into the exhaust and opening up a "bypass hole"... as shown here...
I was looking for pictures of the insides of the M3's exhaust to see if this would be a worthwhile modification.
It could be as simple as inserting a router-bit into the exhaust tip and drilling a hole, but I'd need to see the inside of a stock can first...
Anyone have a stock exhaust with the top cut off?
Be good,
TomK