mrondeau wrote: I'm still trying to figure out why GP and Spec have different BRI's?
I believe it is because 944Spec is limited as to mods allowed and by the fact that a spec tire must be run. The improvements allowed in Spec are generally very cost-effective (like weight removal) and aimed at leveling competition (mostly stock motors). PCA rules allow for GP class to use 20 points of improvements without those considerations, and could potentially yield a car of higher speed potential (by using bigger stickier tires with costly HP improvements). Because a Spec car might also run in GP doesn't mean that it is optimized for that class. The removal of weight is highly penalized in Zone 8 rules compared to its relative benefit. The removal of 350 lbs. from a stock 944 to make Spec weight equals a 12 point penalty alone. That leaves 8 points for suspension and tires (which must be RA1s by Spec rules, no?) By using all 20 points to increase HP, improve the suspension, and reduce weight judiciously, then adding Hoosiers or V710s to the car (ignoring the Spec rules) would result in overall lower lap times (according to the BRI, a GP car should be 1.3 seconds faster than a Spec car in a 1:40 lap).
TT