The advantage a plenum has over ITBs is a broader, flatter torque curve. I had very specific goals for my 3L L6 and one of them was over 200 ft. lb. of torque in a 3,000 rpm band. Given the budget for that engine was $20K Jim Thompson could have used any intake method available - he went with a 1.5L plenum with internal velocity stacks and diverters, 7.5" tapered intake runners, and a 65mm TB. The engine developed over 200 ft. lbs. from 4,000 to 7,500 rpm and over 250 from 5,200 to 6,500.