[hanleyclifford]

76oDay - I would be interested to see a picture or just a layout of your exhaust system. Most of the systems I have seen on this scene have been complicated and contorted, usually because of the requirements imposed by the available space in the boat. The two most important factors affecting back pressure in an exhaust system are 1) number and severity of bends and 2) cross sectional area or ID of the components. The most restrictive component will govern. Just something to think about; increasing pipe size from 1 1/4" to 1 1/2" ID raises crossectional area more than 40% - almost half again.