all trac is us spec 4th and 5th gen.the 6th gen never made it to the us market.
the motor is the 3sgte.
you can recognise it by looking under the car directly from the back,you would see the plastic gas tank.
thats the telling sign for a gt4.
anybody can do a 3sgte swappe and the Hood
and make a gts look exactly like a gt4,suspension,badge everything! but its that one thing that cant be duplicated the view from the back.(the tank)
btw,anybody can buy a jdm 6th gen gt4,have it converted to left hand drive and import it into the states,unless you happen to come across someone who knows about cars they would not tell that its jdm cause it will pass emissions if you do one.(it however will not pass a visual inspection if the person who is doing the test,pop your Hood
and recognize that it doesnt have an egr valve)
as a note, i have seen a lot of acura celica arguments about which is faster,the current 7th gen is not the fastest celica,but,the new rsx s is the fastest integra to date.and it still cant come close to a 6th gen gt4,and if you decide to spend equal amt of money on both cars it gets even more out of the acura reach!