You've gotta be real careful with that. If you wind up with the hole in your exhaust tip plus the size hole you now have in the 'baffle' and you compute the total area, vs. the total area of your exhaust port and they are larger than the exhaust port ( the actual engines exhaust port) you will have screwed up the reflective 'wave' that keeps too much of the the incoming fuel/air charge from spewing out the exhaust oon the way up to the combustion chamber. You will have an engine that has a lousy low end and mid-range transition, with a too touchy needle, the top end always wanting to go lean...not good..
A tach reading with a completely stock OS muffler and the modiified one will surprise you, seriously.
The tuned pipe, or a Jett type pipe arer a much better idea.The idea behind the tuned pipe like alcarafa is running is not about 'decreasing backpressure" or "opening 'er up". It's about optimizing that reflective wave.His motor rips, your's will be a diog ,and I'm not dogging you .
I'd think over this one a little. Doug