I can say from experience with a B1 engine I picked up 3 tenths going from Koffel supplied 2.300 stainless intake to a special ordered 2.300 ti intake only. Stainless exhaust still. Now we changed the radius and back angle of the valve also but never flow tested it. That engine shifted at 7500 and went through around 7800. Intake valves were the only change. Obviously the valve train was not happy.