I recently pulled the risers and elbows to inspect every thing , and I found one of the flappers broken. It was an original 1988 stainless steel pin type flapper. I replaced with the new style replacement kit that has half oval shape rubberized flaps. also replaced split exhaust tube . since these parts replacement it seems like there is a significant increased exhaust backpressure and now occasionaly pops back through carb at no-wake speeds with drive down. Is it normal to behave this way after the replacement of just the flappers? Also lost about 300 rpm on top end. It ran fine before I started replacing exhaust parts 1988 cobalt 223 7.4 mercruiser 4inch exhaust factory y pipe bravo 1 outdrive just wondering if this exhaust restriction is normal and I am just used to free flowing before all the repairs . Sure is a lot quieter now.
