Holes in the back of the muffler???

[jefferygs500]

hey,, i see you guys talking about drilling holes in the back of your muffler and it makes it louder??? i don't think soo?? Or for mine it nevered... I put 7 holes 1/4 bit. Any suggestions??

[V8Pinto]

I started with four 1/2" holes, then drilled 4 more.  That's roughly .2 square inches of area per hole, and 8 holes for 1.6 square inches of area.

You holes are .049 square inches * 7 holes gives you about .34 square inches total.  

I don't think you have big enough holes.  area goes up by the square so even a little increase in the hole diameter will make a large difference.

I could feel the performance increase when I drilled mine.

I might have gotten the math wrong, to much "fun" in my twenties...

[cozy]

I did it. 8 5/16" holes. Too farty. With my ignition advancer it felt like i was losing power. i did't like it and have since gotten a wileyco from Dennis Krook and ordered a flange from Sinrath. I rejetted with 127.5 mains and 40 pilots.