Mufflers on a 604

[mqdirtracer57]

I have Beyea Headers on my crate car. My track now requires mufflers. Which muffler is the quietest,but most efficient? Car cannot be louder than 100 Db

[sj valley dave]

Extreme Mufflers in Ventura, CA work great. Will get our 422 SBC under the state 95 db @ 100 foot rule and flow really well. Here in CA we have a state db limit and they did a lot of research into them....