we've had this thread/argument recently.
My thoughts are that if you are using the stock turbo on yor R31/32/33 gtst, then an R34 GTTSMIC is all that you will ever need.
it will flow and cool more than anything the stock turbo on your R31/32/33 will be able to produce.
This also allows the front of the car to stay open to flow plenty of air to your radiator.
The fact is this.
If you have an R33, an R34 GTT cooler is a direct bolt on.
so you spend $150 to buy one, unbolt stock item, rebolt new item and you are done.
If you upgrade your turbo later and have the need to a FMIC, then unbolt your R34 GTT cooler and sell it for $150.
you lose nothing.
If you have an R32 gtst, you will have to take your stock cooler and your R34 GTT cooler to a place that can do aluminium welding and point at your R34 GTT cooler and say "Make the inlet and outlet on this one the same as that one (pointing at your R32 cooler)"
Pay your $50 and go home and bolt it on.
when you change your turbo and need a fmic, sell your modified R34 SMIC on here for $200 as it is modified to be direct bolt on for the next R32 GTST owner.
you lose nothing.
The fact is that it has been proven to flow and cool well at around 200-220rwkw or so.
an RB20 with stock turbo will get no-where near this.
an RB25 with stock turbo will come close but not reach it.
FACT - Colder/denser air = bigger bang, which = more power.
fair enough.
going by that taking your stockish car to a dyno run, doing a run, then installing fmic and doing another run "may" show a higher power figure of a few kw.
But what it won't show you is the loss of throttle response.
if you don't increase the boost, it will feel shit.
Notice I didn't say lag.
if your turbo was getting full boost at 3000rpm before, it will still do it with a FMIC.
I say throttle response.
as in idling along then planting your foot.