Hi-Tek set of stainless exhaust headers for Chevy small block marine engine. If you don't know what these manifolds are, then you probably should not bother reading further. It will be a long read, as I want to be thorough and honest.These are for any Chevy Gen 1, Small Block V8 based marine engine. 305, 350, 383, 400. Volvo, Mercruiser, Crusader, etc.Years ago, I tested all the best known high performance manifolds in the market, by running them as they are supposed to (water cooled) on a dyno. Yep, that cost me a pretty penny. I compared these against Stainless Marine, Custom Marine, Eddie, Marine Power, CP Performance, and Mercruiser. Ran all on a marinized 383 putting out 430 HP and 470 lbs-ft torque. On performance alone, these came in second, surpassed only by Custom Marine, and by a mere 3 HP. These were $2,300 a pair, Customs were $5,000. These were still cheaper than Stainless, CP, Eddie, and only slightly more than Mercruiser and MP. They were the lightest of the bunch, under 30 lbs for the pair, as opposed to 150 lbs for a set of Mercruisers!!! And the air around them ran about 25 degrees cooler than the rest (imagine that difference in an engine compartment). More importantly, when I ran an infrared spectro on them, these showed even heat distribution all around, while the others, except for MP and Eddie (which are aluminum) showed lots of hot pockets, aka, future cracks are coming fast. I chose these for my engine building project. They are a great idea and well designed, BUT!!!Manufacture quality is great on the manifold itself, the welding is top notch, but the quality control on the fit is somewhat uneven. Of the 8 pairs I bought, two had small imperfections on the flanges. When I contacted the owner in Australia, he refused to honor the warranty and called me a liar! It was easy enough to file down the flanges but this absolute BS of a customer service turned me off this brand. They have rebranded recently but I hear they're not any better. This pair has sat unused with me for several years. I have planned to use it but don't have a boat where I can fit them, so it is time to let them go.They are in great shape, have only been used as demos during boat shows on non running engines, never ran, and are a great performance addition to any build. They will add horsepower, eliminate the need to run antifreeze through the manifolds (they run with exhaust raw water), can be used with fuel injection (they have oxygen sensor bung hole on each manifold) and, yes, will look really good.THEY ARE NOT UNDER WARRANTY! AS IS PURCHASE. NO RETURNS. They were bought in 2017 I think, and although their site says 10-year warranty, you already know what happened to me. Still, for performance gains, weigh savings, and cooler temps in your engine bay, they are awesome! They sell nowadays for $3,300. So, $1,800 is more than fair.