You've got my interest. I'd probably even make the drive to do the install. Heck I drove to apr for their free install. Back when they did that at the bbq. Don't like the performance shops here.
How does it do on a car with weak valve springs
I don't know. I would assume if other companies have big turbo kits with weak valve springs working just fine, this is the same.
If it's installed in shop, it even has a tubular manifold for even BETTER flow. I would assume it would be no issue.. I think that was just for K04 and GTX28s.