www.iFourWinns.com

A very valid point !!!!

But a cast aluminium riser would be ok and wouldn't corrode to the same extent as the cast iron ones do. Apart from the material cost, they must be cheaper to produce as the aluminium allows melt at a much lower temperature than cast iron.

I have the now obsolete OMC 'batwings' (one piece manifold/riser). I would love to get a one piece in stainless steel if I re-power with a new engine. The one piece must have been more expensive to cast but never had problems with leaky riser gaskets.

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88 Four Winns 200 Horizon
4.3 OMC Cobra-4bbl
2002 Walker Bay 10/2012 Suzuki 2.5
2008 Walker Bay 8

1998 Jeep Grand Cherokee 4.0/Selectrac
2007 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II

What about these??? Not sure, never used them, but sounds good.

http://www.perfprotech.com/blog/articles/marine-exhaust

The Hi-Tek Marine manifolds are not cast stainless.
They have a laser cut flanges, stainless tube primaries (4-2-1 design) and stainless sheet metal cut & welded together around the primaries, as the water jacket.

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2011 Four Winns H180 SS.
Aussie built Mustang 2800.
SOLD - 1997 Four Winns Horizon RS

My 2000 Vista 298 has about 950 hours on each of her twins and I only run in fresh water. Why has not my tech not brought this issue to my attention? Is this what I will see if I take my manifolds and risers off? I had no idea American water did this much damage.

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Current Boat: 2000 Four Winns 298 Vista
Previous Boat: 2000 Carver 406MY