I have a 04 f6 ext efi with a 58/52 angle helix in the secondary stock. I've been thinking about trying a multi-angle overdrive helix from slp to gain a little more top end,I get aound 88-94 depending on conditions. SLP recomended a 60/53 helix. Is the first number(60 degree)used for initial out of hole and the second# (53 degree) used for shift out. Any info is much apreciated. I don't want to lose to much out of the hole. :beerchug: