Anyone heard of or tried Marine Power manifolds? I was looking at reducing some weight out of the back of the 18 and GLM Aluminium SBC manifolds have not been available for the past 1.5-2 years and one company I talked to offered these as a comparable product. They are not listed individually on Marine Power's website but they say they are "Semi-Tuned Aluminum Exhaust Manifolds." At $600 they might be worth a shot, anyone used them before or have any experience?
http://www.marinepowerusa.com/skitow_5.7liter.php