I have wondered a lot about many peoples who uses BIG turbos on their engine.
A friend of mine runs a T4 on a 91 Sierra Cosworth 4WD.The engine puts out 400hp at the crank but its virtually powerless below 4000rpm.can that be pleasant to drive in the long run.

When i bougth my Turbokit i had a long diskussion with the dealer.The kit was orginally delivered with an Garett T25 usable up to 220hp.I told him that my goal was about 250hp (i want maximum driveabillity and reabillity since the car are a dayly driver) and asked if a T3 would be a good choice.the answer was no,he told me that a T3 would have rather slow spoolup time and would affect my cars driveabillity.The other alternatives was T28 (280hp version) but it was too expensive and an IHI RHB 5 (280hp version) was also a great bit more pricey.
The final alternative was a Schwitzer unit supporting 260hp.The price was equal to the T25 and according to the dealer give me the same spoolup time as the smaller T25.

I must ask can you get a smoth and drivable engine with a good low end if you use one of the huge turbos many people uses?