I have one of the original II Much vents and like it a lot. Others are using the Finch dual (fuel and rear) vents http://www.finchperformance.com/ Yeah, they are pricey but they work really well. I haven't heard too many good reviews of the tanks inc vent.
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Chris
1968 Camaro SS
LS3/T56
Full of DSE and Holley parts
Brian Hobaugh SCCA National Tour June 2014
First Hemi 'Cuda Convertible Ever Built
Short clips: Goodguys Pleasanton autocross and pit videos
Fuel vents
Threaded Mode