Nyroc Mod holes: 12 inch deep vs. 18 inches deep
 

I am trying to decide how many 1/2 inch holes to drill in my muffler and how deep to go (my local Lowes sells both the 12 inch and 18 inch drill bits).

For those who have already done the Nyroc Muffler Mod, how deep did you drill the holes? 12 inches or 18 inches?

Nyroc Mod holes: 12 inch deep vs. 18 inches deep
 

A 12" drill will do it. I drilled 6--.375" holes. If you want loud, go to 6-8 -.500" holes, your choice. I like the mellow, growl of the 6-3/8" holes . I can be quiet when I want stealth.

Nyroc Mod holes: 12 inch deep vs. 18 inches deep
 

TRX450,
I am definitely not interested in making my neighbors mad at me and drilling some 3/8 inch holes appeal to me for that reason...but everyone tells me that the 1/2 inch holes provide the biggest performance gains...so I am wondering if only three 1/2 holes would be a good compromise for me.

Getting back to my question...the muffler seems to be much longer than 12 inches and thus, I am wondering if there is greater performance to be had (freer flowing exhaust) by drilling deeper than 12 inches? What do you think?

Nyroc Mod holes: 12 inch deep vs. 18 inches deep
 

Mikey--- The 12' drill will go thru ALL the baffles that you need to go thru. nyroc and I both did the 3/8' X 6. I imagine 1/2" X 6 will do you just fine. GO FOR IT! It'll sound very throaty, but NOT obnoxious.