Funny thing about Intercoolers.. They dont allways give you a gain in "KW" but they do let you turn up your boost a tad so you should gain some performance.
My friend has just fitted a china cooler to his R33 and without doing any other mods, no boost increase he lost 5 - 10 hp ( After turning the boost up he gained a bit and its nice and cool now ) just keep in mind your making the air travel around all that bling.