I am looking at the same thing on my 4.3 . There is a company called GLM that makes many aftermarket parts for Mecruisers He has a running ad on E-Bay right now for around 650.00 plus frt.I will be changing my old 1 piece exhaust manifolds this fall. 2001 4.3L Mercruiser Alpha. I don't see a complete kit for this at iboats. Where can I find the the best deal on a "kit" for this upgrade?