Gouky Engineering is actually "Frankenstein Motorworks" if you ask the state i currently live in.
as for the final drive stuff, i'd not worry about it until you've truly decided you aren't going to go 6-spd. the motor won't care much about spinning a little higher, it sounds a little angry about it, but it'll do it all day long and still get pretty good fuel economy. in an MKI i bet it gets over 35UKMPG with stock 4.285 gears on the highway.
if you do find 3.625 gears, don't worry about it taking the shock and awe away from the car. the torque still comes on hard enough to make 1st gear useless.