My race engine builder, Bill Noble, who just won the SCCA Runoffs in FV for the umpteenth time, told me that he ran back to back tests on the dyno with Bosch and Splitfire and could not measure a difference, except of course in price. YMMV, and I do not have any financial interest in Bosch except for when they are on sale. Steve Fox 87 325iS 86 R65 ?? Zink C4/i FV