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The stock TT oiling system consists of two bypasses in series. The first one is internal to the oil pump, the second is in the oil filter tree for the oil cooler supply. By design, the oil cooler bypass opens well before the internal oil pump bypass in order for the OEM oil cooler to function properly. Those that have deleted the second bypass using SPL's oil cooler setup report 100+ psi IIRC, which tells me the internal oil pump bypass is set to approximately 100 psi. With the second bypass functioning, oil pressure tops out at roughly 60 psi when things are warm. This tells me the oil cooler bypass is set to approximately 60 psi. As a result, I estimate the differential between the pump bypass and the oil cooler bypass to be about 40 psi. While I agree porting the pump may result in slightly less pressure drop through the system, I'm fairly certain it isn't enough to overcome the 40 psi differential between the two bypass valves. Therefore, in the Stock TT oiling system, I don't believe the oil pump bypass will open prematurely as a result of not porting the pump, which will result in no lost flow. Furthermore, I believe that the main reason for the higher volume of the TT oil pump is to force an overflow/overpressure condition for the bypass design of the OEM oil cooler. Aside from the oil cooler and turbo oil supply requirements, I don't believe the TT requires the extra flow. Therefore, for those that delete the OEM bypass oil cooler, there is likely a large excess of oil flow that is causing the internal bypass to open frequently anyways. Unless the relatively small amount of additional lost flow from NOT porting the pump is greater than the volume differential between the NA and TT oil pumps, I don't feel this is a valid concern. Additionally, once the oil pump internal bypass opens, additional lost flow through the bypass valve will not result in a reduction of flow to the bearings because the pressure stays constant.
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