I can confirm that 90-91 calipers have larger pistons than 88 calipers... but I can't confirm that they're the same size as DA. The rear calipers are the same DA vs. EF, so it doesn't make sense to me that a CRX Si would ship with a 2040 valve and and a DA would come with a 4040. Why would Honda make two parts if the brake systems are the same?