[Tom Goldman]

Why even use the Vortex cones, unless you like the muffled sound .
NHRA has quietly let the muffler deal die an unofficial death .
Many racers, myself included have'nt run mufflers in years.
After cutting a brand new slick with a piece of a muffler core ,and nearly crashing ,I took my mufflers off,threw them in the nearest trash can, and hav;nt had any since.
You should look to relocate the O2 sensor in a primary tube anyway for a more accurate reading ,per Racepak.