Every turbo is a compromise. One that performs really well on the bottom end will fall on its face on the top end. One that makes big numbers on the top end will suffer off the line. An engine speciffically designed from the start for a turbo will have a wider power envelope over an NA engine converted to a turbo. Oddly enough, it is hard to beat a stock NA cam profile with a low to mid boost turbo. The worst thing you can do is to install a blower cam in a car with a turbo. They just don't work the same. I have seen a car making good power fall on its face after installing a blower cam. The problem is overlap. Too much and the turbo boost will fall off as it is blowing the charge straight through the cylinder just as if you opened up a vent to atmosphere. For street use, I like a turbo sized to make big torque numbers early and then drop off in upper rpms. How often can you wind it out in normal driving? My 300C running 7 psi (5.7 HEMI), went from about 220 ft lbs of torque at 3200 rpm to over 500 ft lbs of torque and picked up about 120 Hp peaking at 411 up at 5200 rpms. This took a stock 4200 lb sedan from about 6.25 seconds 0-60 to 4.18 seconds 0-60, and from 94 mph in quarter to 110 in the quarter.