Hello all . I have built a rb25/30 the car runs well enough and revs fine and smooth . The only problem is there is a top end noise . We think it's the lifter . Also have put lifter cleaner in , We changed the lifters taken them out and fully cleaned them. It got better, but was still there and slowly got worse. Now there is a consistent knock. No distinct area of the noise . We don't know if it had a restrictor or not . The head has the vct mod and all . Would any one know what the problem is or even what we could do . I'll also try up load a video on YouTube