that reducer allows a std speedo to work with just changng the number layout to read to 145
the speed the ecm sees with that reducer is off by roughly 40% slower than actual because the speeo cable is spinning slower , it also screws up the lockup speed if you have a lockup trans it wont activate lockup until you're over 80mph
you need to remove it and have your speedometer properly calibrated
or install an aftermarket inline vss sender(and buffer) before the reducer
, check with casper electronics for the vss and buffer.