the_invisible wrote:I am thinking about spending all my money on headgasket and fully upgrade my valvetrain.
But will the valvetrain upgrade increase HP itself? Or is it just a better insurance for higher RPM and boost?
Most valvetrain upgrades are insurance against problems at higher RPMs and higher boost levels. As part of my Stage I build-up, I'm doing valve springs, rocker arm stoppers and a 1.2mm metal head gasket. None of those are going to produce any more horsepower.
Cams and adjustable cam sprockets will help your engine make more power. Your best reference to find out which cams are good for your car, would be to look at other vehicles with similar power levels, and figure out what they are using.