Re: Can I use a different type of exhaust manifold.
In 1991, OMC switched to a 2 piece design, I'm not sure if you can just use those on your engine but they were used on both the OMC Cobras from 91-98 and the joint venture Volvo Cobra SXs from 94 and on up. It really depends on the angle and height of the Y pipe as to whether it will all line up. There is a conversion kit that is sold for those models (with the one piece batwings) using Barr manifolds, that is pricey but will work fine (last I looked $1200 for parts). There is also a kit using GLM manifolds but they have had some leak issues. I have used the Bat wings on mine and they have never let water in the engine, no joint to leak. Personally I like the one piece better because you don't have that achilles heel gasket that once it starts to leak a bit of salt water it erodes the sealing surface and then you get water in the cylinder. I want to find out if I can adapt the Merc dry joint units to mine when it needs its next manifold change. To me that eliminates the weakness of the 2 piece design esp in salt water. In fresh its not such a big deal.
What I might try, is if you can get the parts for a Volvo model (like a 94-96 or so V-6) just one side, locally, if you can return em if they don't fit, just fit em up and see if it lines up. Shipping on exhaust is expensive because of the weight. Then if it fits get the other side and away you go....Merc parts maybe could fit, but I think because the Volvo used a very similar Y pipe to the OMC the probability of it fitting is much better.....
