I want to add a manuel oil pressure gauge but I want to leave the factory gauge hooked up. I know some have put one at the back of the motor in the other side from the factory hook up.I know people have done it, I just want to put a short pipe and mount it at the back of the intake. What size pipe and adap. do I need to do this. This may save me 20 trips to the store to get the right stuff. Thanks for any help on this.