Stock 1972 340 intake and Thermoquad HP limits..?

Id say the stock is better than some of the lower end aftermarket intakes. Id say asking the limit of hp and torque is the wrong question. Obviously the more air you try to pass thru (rpm) it the more its gonna cost power over a more suitable intake. Theres gonna be less difference in a 300 hp motor than a 550 hp engine. At say 400 hp you might be given up 20 -30 hp over an airgap. And probably only at the top part of the powerband, the stock might make more under 2500 rpm. Its up to you if that matters.