My rule of thumb for intercoolers on a R33 GTST are. If you plan to keep the stock turbo (no high flowing etc.) The R34 GTT cooler is a good choice as its efficient for 200rwkw, cheep, easy to install, and you don’t sacrifice any throttle response.
This is not to say you wont benefit slightly from a larger cooler at this power level but the trade of is throttle response. Fact is though I didn’t find the response much different between the stocker and my hybrid super monster but many other people have noted a difference.
I believe the reason people sometimes find that the car is slower after the bigger intercooler install is the fact that it runs extra rich the ecu sees way more air and richens the mixtures. Get your AFR's sorted then you will notice a huge difference. The intercooler plus tune made a huge difference to my car.
Sure people have run 12's using the stock cooler, but what tires where they using, what suspension setup did they have, how good was the driver, what were the track conditions, there is much more to drag racing than power.
To do this properly get a car, same driver, suspention, tires, track conditions, stock cooler with engine management tuned to suit extra boost, exhaust etc. have 5 runs take the average time.
Keeping everything the same exept for a upgraded cooler and a ECU tune to suit the extra air flow. 5 runs take the average time.
Ill bet my bottom dollar the car with the upgraded cooler will be signifitly quicker.
cheers