i copied a small piece...
The stock exhaust ports fail to flow any more air at
about 8mm of lift (0.317"). Increasing high lift flow is the first thing on the
mind of the man holding the die grinder. Still there is not a lot to be gained.
For these reasons, staggered cam sizes seem to work well in the Supra. A
longer duration exhaust cam combined with a shorter duration intake cam can
yield surprising results. Never forget, your cams must compliment the engine.
Part of that is recognizing that valve lift over 8mm on the exhaust only
promotes valve spring failure. For that reason, I don't recommend exceeding
stock lift on the exhaust side. There is no advantage except in the driver's
mind.