I uncorked my beautiful hand welded stainless steel Skorpion exhaust with a 3/4" steel grade stake, like the ones used on construction projects to hold concrete forms, string layout lines, etc. Also, they are tempered to be beaten on without cracking or shattering... good idea for this job.
I keep three of them in various diameters for just this purpose.... 1/2",5/8" and 3/4". I prefer the 42" stakes for more accurate aiming control and added kinetic energy, but it is probably like choosing a snooker stick... you know, tastes and preferences differ.
I always stake them from the inside (with the exhaust flow) when I can, depending on the curvature of the muffler and the location of the baffles. It traps less exhause gas and helps the natural flow at high RPMs, too.
Sharpen the stake on a grinder to make a very sharp and gentle taper, elongating it to go from a zero sharp point to full diameter in about two inches. Grease it liberally so it will rotate easily and not get stuck.... as you begin your first gentle strikes against the baffle plate, make sure you are hitting center, and continue to bump it back against the identical dent... very important. You now have a slide hammer that will eventually penetrate the plate... so be cool and gentle and slide/bump/rotate until you penetrate the baffle. Regrease, rotate,repeat. When you have pierced the hole to the diameter you desire, you have retained a beautiful stock system and probably gained some horsepower, not to mention maybe a better sound.
#1 caution is to be cool,deliberate, and patient. Use a channel lock or large pliers to rotate the stake, keep it greased so it doesn't stick, and be aware that you may be pleased with a smaller hole. You can always repeat the process to enlarge it but you will have problems closing it down. Remount and experiment if you want to find out what you have just done, acoustically.
Looking at the diameter of the hole you have just pierced is as easy as looking at the grease ring on the stake cone.
Keep the tip sharp so you don't pull away poorly welded baffles... you want to CUT the metal at first, not pull it away from the sides of the muffler, or cosmetic damage or an asymmetrical deformity may result.... ruin the beauty.
The #2 caution is to make sure you are aware of the depth and angle of your penetration, take measurements to make sure you are not about to generate a dent in your beautiful muffler from the inside.... again, be cool with this process.
It won't lose you any weight, but it will gain you some torque and probably horsepower, and it might now sound like a thumper oughta, and save some money. A substitute for this process is an elongated drill bit,but you should pop a tip guiding dent initially so the tip doesn't wander around before it penetrates the metal. Also. the drill bits will limit your diameter options, unlike the stake.
I looked all over for a Skorpion muffler that looked as beautiful as the original to my eye. My eye said nothing was out there, and especially hand welded in stainless steel, though an early carburated Suzuki SV 650 came close. I pulled out my collection of trusty old exhaust spikers. Worked like a charm, as always.
Old American Hot rodder trick to avoid tickets from cops who use flashlights to inspect for illegally installed too loud exhausts. "Yes Sir Mr. Officer, as you can see, those mufflers are dead stock factory units"
PS. Don't tell anyone else about this... I would hate for this deceptive outlaw mototrick to get out to anyone else but you. Intercontinental exhaust motolaw abuse regulations might kick into the equation, and we would all be exposed as dreadfully rebellious moto outlaw criminal types, an be inna heapa trubble.
Mumz da word... OK?
