The overall diesel engine performance is very much dependent upon the design and operation parameters of the inlet and exhaust system. This study was undertaken to provide knowledge for improving the diesel engine performance through modification of the exhaust middle pipe configuration. This study presents the results of an experimental study of the exhaust middle pipe on diesel engine performance in terms of torque produced, brake horsepower, Brake Mean Effective Pressure and the specific fuel consumption. Experimental study is adopted in this study based on two conditions, at 50 throttle opening and 100 throttle opening conditions. The experiment was conducted on a four stroke, four cylinders, in-line OHC and indirect injection diesel engine with different exhaust middle pipe configuration attached. The results of the physical testing shows the differences in engine performance for different exhaust middle pipe configurations especially at the engine speed greater than 2000 rpm. © 2011 Asian Network for Scientific Information.