I am not a big fan of "Brian Crower" stuff. The original company was "Crower" and it was the father. The son started the "Brian Crower" spin off for imports and a lot of it is cheaper Chinese stuff sold at a markup.
If I was doing it I would look at Ferrea or Supertech. Both have complete valve trains for the 1FZ. The Supertech valve springs have options that go from 160lbs of open pressure all the way to 226lbs @11mm, so you should be able to easily find an option that fits.
The Ferrea stuff is also incredibly high quality and who I chose. Their dual springs are rated at 175lbs
@10mm. The only problem with the Ferrea springs is they are not the same height as stock so you need their entire setup, valves, retainers, spring seat locators, etc.
Dual springs help control the harmonics better than single springs, if you are going single look for a beehive shape.
Really the talk should center around your goal and how high you are going to rev the engine, and then pick your components from there. For example you could make 400hp on the stock engine and valvetrain. I am doing it in my grey cruiser.
Once you start talking about really big power, your going to need to take a look at what you are going to do for a transmission. As of yet no one has stepped up and ATF Speed'ed their A343F, but those guys figure their A340 builds can hold 800awhp. But they have gotten a little more famous with their automatic running in the Baltic Supra which made 1150whp. So the cost has increased from $2999 to $3499.
