Hi Everyone !!! I have recently upgraded my Cultus to g15b japenese engine. I am having a little problem. The car is missing from 3500 to 5000 rpm, as soon as it crosses 5000rpms it boost like it has been turbo charged. I am having this problem from day 1. No mechanic whatsoever could able to locate the problem....Anyone who can tell what to do with this that would be helpful. Thnxxx