Not really, just the first pick I found lol.
Of course you lose low end. Your are trying to make horsepower! Not lowend torque. You gotta tune and match your mods. Cam, intake, header, port work, ect all have to work together. As in be designed to increase the power made in similar rpm ranges. Back pressure is not needed on a N/A motor to make power. You may be confusing back pressure with exhaust velocity, wich is used for port scavenging. Go down to your local 1320' and you will see most of the old schooler american v8s are racking long tube only. Small blocks and big blocks anywhere from 350hp on up. They want there motors making power WAY up high. My old boss was shifting his mild BBC at like 7500rpm.