Well they (VMP) wanted me to use a SCT and not a Ngauge if I bought a Loki kit?
I don't think the Ford-Roush relationship works like that. Ford isn't paying for drivetrain warranty work once a Roush supercharger is installed. Ford may be performing the work, but Roush (or their underwriter) is paying them to do it. You have to file the warranty claim with Roush (though your Ford dealership might be courteous enough to do this step for you). Ford doesn't sell the Roush vehicle as a Ford-branded product and it doesn't go through the OEM engineering and testing process as a Ford performance vehicle would. If you look up the fuel economy numbers, the Roush supercharged vehicles fall under Roush Performance, not Ford. Ford dealerships also sell the Shelby Supersnake, which includes the Whipple supercharger and a 3 yr 36k warranty, but I wouldn't consider them to be same business entity either. Roush did pull the genius move of integrating into the dealerships and making warranty work more seamless from the customer's perspective, and they deserve credit for that.
This is true. GDI usually allows you to run about 1 full compression number higher than PFI. Consider that the highest compression OEM boosted PFI engine I can find is 9.5/1 (Predator, Hellcat, etc), but the highest GDI is 11/1 (BMW B58) and Honda 1.5T (10.6/1). NA is pretty much same, with the PFI Voodoo running 12/1 and Mazda going 13/1 with GDI, and the Mazda is designed for 87 octane. I believe Ford didn't put GDI on the Predator simply because they didn't need to in order to reach the power, fuel economy, and emissions goals.
I'd love to see this actually tested. Problem is, the 2650 kits are all spinning them faster and making more boost than the Whipple (with the supplied pulleys). Whipple Stage 1 is 9 psi, Stage 2 is 11, Roush is 12, Edelbrock Stage 1 is 13, and Stage 2 is 16. I've done the math and it is true that all of the 2650 kits are trying to cram more air in than even the Whipple Stage 2. To get the same ACFM airflow, the Whipple would have to drop down from 3.875 (Stage 2) to a 3.55 pulley. I'll be very interested to see what pulley the Loki kit comes with for comparison, as the boost level could be a bit misleading due to restriction in the stock TB and airbox/filter.
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If I understand this stuff correctly, which I may not, boost is a major factor obviously but max cyl pressure is also a function of spark timing and definitely cam phasing (which can alter effective compression ratio) for a vvt engine, both of which are controlled in the tune and are likely different between the different sc vendors in their canned tunes at a given rpm. It may be hard to compare kits by boost level alone. Some vendors may be more aggressive with cam/spark at different rpms than others...
