Jeep exhaust Manifolds instead of headers, are these the large opening manifolds?

Are these even worth the trouble or will a pair of shorty headers work better? Which are recommended, the Summit block huggers? DODGE Summit Racing SUM-G9064-1 Summit Racing™ Block Hugger Headers | Summit Racing
I don't want to lose any low end power for a street car.
Then add a 100 shot of nitrous, cheapest hp out there