I am instaling a oil pressure gauge and i am wanting to know if i need to T it off and put bolth sensors there or if i could get away with just puting the aftermarket one in an leaving the stock one out for space issues but would that mess anything up for the computer readings?

 

a brass T is what you need if you want to run both the stock sending unit and the oil pressure gauge sending unit. if you don't reinstall the stock unit the only thing it will affect is the oil dummy light in the gauge cluster.