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was just wondering if there could be any adverse power losses due to this? bolted a skunk2 ultra street manifold onto my stock k20a2 last month along with a 70mm tb, car already had a k tuned 4-1 race header and a 3 inch system and kpro, car made 226bhp on an accurate rolling road which my friend went to a few days later to the exact same rolling road with a stock rbc with oe throttle body, ebay exhaust manifold, centre section and a stock rear box and made 232bhp, dyno operator said my car was making peak power at 7.9k which he found unusual considering hes done a fair few cars with the same spec and the all make peak power around 8.4 iirc. been looking over the car since and remembered when fitting the skunk2 intake that the thermal gasket provided with it was the worst match ever which i sanded down to match the intake so i thought id have a look down the runners and noticed every port has a step on the bottom and round the sides, ive tried googling it but i only ever seem to come up with the manifold port being smaller than the head port doesnt matter but in my case the head ports and smaller than the skunk2 ports or the manifold its self is slightly off centre of the head ports but even then a step would still exist at the bottom of the port
 

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This is a bit exaggerated:

A step change like a large manifold runner entering a smaller port creates turbulence zones that effectively reduce the size of the intake port to a smaller cross sectional area than the physical geometry of the port.
 
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