OMC exhuast manifold conversion

[Redrig]

I have discovered that I have a leak in one of exhaust manifolds, on the outside where I can see it, so I can only imagine that it is dumping water into the exhaust passage as well, after doing some research, the current manifolds are the rear riser, 'log style' My question is has anyone ever used one of these covnersion kits?

http://cgi.ebay.com/ebaymotors/OMC-...9236877QQptZBoatQ5fPartsQ5fAccessoriesQ5fGear

it sounds like there are performance and MPG gains on using these style manifolds rather than the rear risers.

does anyone have any experience doing one of these conversions?