I'm totally with you on that!!!! No doubt the exhaust pushrod and cam timing are critical to boosted engines. That is a REAL thing to worry about.

Just making the point that a stiffer spring isn't as much to worry about though. On a boosted motor, the intake MIGHT like a stiffer spring during closing because of the marginal difference between cylinder pressure and intake pressure at peak RPM. The exhaust valve MIGHT want a LESS stiff spring due to opening the valve under high pressure. The exhaust valve MIGHT want a stiffer spring to fight against higher back pressure during closing.

Just pointing out there are a lot of "MIGHTs" in there that probably don't really mean much of anything in the end.