If you already have exhaust work done I wouldn't go with thw GT40 P since you have to change your headers. With the GT40 heads off of the 94/95 Cobra plus your other mods you should be in the 13's
I would just replace it because once it has been reserfaced it becomes weaker. A new one from Steeda is only about 95-100 bucks. Well worth it!! I have a Spec Stage 3