Now i'm not trying to say that you can't run 9's or 10's with your manifold, i've seen it done. Differences here aren't going to be major. Just pointing out the ideas I went by. Most people use ramhorns when they need the turbo flange to be so high that a manifold like mine with a high angle merge collector isn't practical, like in a lot of hondas. They prefer extra bends and longer runners to a crappy merge collector, cause a good merge collector is more important.

Stuart