Starting to Learn on 95 G30 5.7 for Towing

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Also a further discrepency I see is the fact the 300 HP marine TBI Vortec engines used the same cam and a GMPP Vortec TBI like manifold except without EGR provisions with 2" TB openings and 454 TBI unit. With restrictive marine wet exhaust manifolds they were NET rated at 300 hp and 370 tq. Even at 300 hp you are barely being restricted by the stock small block TBI unit as it only becomes a slight restriction in stock form in the 275 hp range and is capable of 325+ before a 454 TBI unit becomes noticeably stronger.