I have used them in several applications after a lot of testing. As the race tracks we ran on lowered their max decibel levels ... we needed to find a solution that cost us the least power but got us down to the target db .... which was 90db max at 50'.
These diffuser cones work well ... but only in the right location. When we tried them ANYWHERE in the exhaust system .... before the mufflers, after the mufflers & at the tips ... they hurt power big time & only reduced the sound a little. When we tested them where they were designed to be ran ... in the header collector ... power loss was minimal ... and sound reduction was significant.
The other key to reducing sound without killing too much power is ... of course ... proper muffler design. We tested 6 mufflers to find the best option for 410' Sprint Cars, 360 Spring Cars & unlimited cube NASCAR Modified engines. The Flowmaster mufflers tested best. The more I worked with the Flowmaster guys ... taking their recommendations ... the more power we kept & the more sound we dropped. With Flowmaster race mufflers ... the larger the muffler ... the less the power loss ... and the quieter the engine.
On the NASCAR Modifieds ... we ended up running 12 x 5" x 18.5" mufflers (huge) ... combined with the Dynatech diffusers in the collectors. We dropped the sound from 103db to 89 db ... and the power only dropped from 597 to 576. And this gave us an advantage for awhile ... until everyone else in the series figured it out too.
Best wishes.
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Ron Sutton Race Technology
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Brian Hobaugh SCCA National Tour June 2014
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