Well our pair of 8.1s had failing exhaust manifolds early last fall. this caused us to have to pull the boat and miss the fall Black Sea Bass and Striper seasons. We pulled the starboard first because it was the worst and we did not know exactly what we were in for. What a job replacing both exhaust manifolds. what we learned from that engine we used to work on the port engine without removing it. The outboard manifolds on both engines had be replaced with both inboard manifolds being significantly reworked. Additionally there were a zillion little (and not so little) items that had to be addressed. Out of 32 exhaust manifold bolts, half of them broke off. We also increased the depth of the thread by about a 3/16ths inch allowing a slightly longer bolt. After couple short sea trial runs, we took our Black Fin Combi offshore last weekend. Our hard work paid off with both engines, and the boat overall, running without a hick up. We also limited out on Black Sea Bass. Yahoo!!