i have used offy intakes since the 60's.each engine will not react to mods in the same way but for the 429-460 i have found that if you cut back the intake runner about 1/2 inch and taper the runner in the intake ports you will gain both performance and driveablety. plus they respond well to 2 inch spacer 4-hole type.the 360 degree intake is really better than the 180 degree intakes.you get a smother idle and there was no lag.