HELLO ALL, I AM LOOKING TO CHANGE MY EXHAUST PIPES FROM STOCK TO THRU HULL. LOOKS EASY TO TAKE OFF RUBBER PIPES AND CAP OFF Y PIPE ON MY MERCRUISER V8 305 GM MODEL 228R. NOW CAN I ADD MY NEW EXHAUST PIPES GOING UP HILL LIKE OR DO I HAVE TO STAY LEVEL OR GO SLIGHTLY DOWN HILL?<br />THANKS JEFF