[N1ceDrgn]

It comes down to the application and a little personal preference. If you are running with a smaller, stock-size turbo, a smaller turbo is all you're gonna need. Otherwise the amount of lag you are going to experience will be more of a handicap than an irritation. If you are using a larger turbine, be it a T04 or T67, then a larger intercooler would be a good move. I was running with a hybrid from Turbonetics and my engine after I got it bored over, the larger 3 core intercooler I have was needed, a little for what I had at the time. It is needed for the T04 and waste-gate I intend to use.
Now some favor a smaller intercooler for drag racing and drifting, with a smaller intercooler, the 'turbo-lag' is nearly eliminated for the most part. It is still there but it is reduced a lot because the amount of pressure is the same, 'under boost'. However with a larger one, you are filling a larger space, so the pressure lag will be more noticeable. Like I said though, there are compromises that need to be made. Less flow, and less lag, or more flow and more lag. Another way is 'some-what-restricted' air flow, or none. Take your pick...