Well if you aren't planning to run a turbo setup to push you over 700hp you'd be wasting your money...
Unless you're at Jesus' level of power you will see more gain from some light bowl work. The valves and runners in the stock head are already very well matched and that's why so many guys get great numbers out of stock motor Supras with a decent turbo kit and fuel...
It all snow balls, I know... if you go with just 1mm oversized Ferrea valves to get any gains out of that one mod you'd need to open up the runners, run different cams, and a big-ass turbo with plenty of fuel to get the top end breathing necessary. And the bottom end driveability tends to suffer.
It all depends on how much $$$ you want to put into it.
Ya, my bad, I didn't mention that unless you're going for HIGH numbers then it will make little difference. I have the same opinion for upgraded intake manifolds.
okay fine.. what do you guys think fi I just do the stem seals and call it a day.. dont seem to have any other problems.. I was going to do this becuase i wanted to do all the head a the same time..
dont plan on having crazy amounts of power.. im aiming around 500-600 hp max.... so by what you guys are saying then the headwork wont make any much difference..
probably get the valve seals done and put a set of cam gears on..
Go to t04r.com and scroll through the tech section. There's a very good article dedicated to the MKIV's head and performing some port/polish work. It's a very thorough article and explains a lot.