Sorry but missed some info as the notches might work on street use, they will not work for drag application as the gain is in the low rpm's like under 4500 rpm.............like i said the guy i know swears by it but in his case is low horse power units were he is actually after the gas mileage more then anything else...i know he told me on his chevy v8 truck he gained close to 5 miles per gallon........so take for what ever its worth i am not doing it either