It depends on what you expect from the 2 x 1 carb setup. On my 1954 sedan with a 235 engine, adding a 2 x 1 with Rochester carbs added 8 m.p.h. to my 1/4 mile speed at the drags. I went from 77 mph to 85 with no other changes. Stock exhaust manifold with 2nd outlet added between rear two exhaust ports on both carburetion setups. Mileage went down about 2 m.p.g. but I thought the extra power was worth it.