Well I ant gonna lie to ya bro but I ran my mill with the 7mm insert from werks(came with mill) at say 80% tune on the street(still waitin for outside season) then the GRP 6mm insert. I can see the difference between the two at this tune, only to get better with the race tune natrually. I'm not gonna pull your chain, I have been doing the nitro scene for a whille so I can tell when a mill is in the sweet spot without a track( I tune for performance not longevity) and the GRP 6mm insert has a good gain on time over the 7mm insert. Now take to mind, I am running a 2053 pipe( known for milage, not performance) This year I am after LONG runtimes not tire shredding performance(been down that road, cost too much, that dont win races) also with this type of bottom end, thinking of going the steel flywheel route on a eight 2.o RR. The fuel savings is awesome, but if you are willing to go with the less bottom end you will not be dissapointed. I look at it like this, hey dang you cleared that tripple NICE but where you at the pits oh, well im still on the track makin laps feel me? I have no reason to believe that a Odonells 97T plug Odonells 30% race fuel and 2053 pipe coupled with a GRP 6mm insert with carefull driving should give me 12 minutes of tank time