Get more out of OHC below

Hi to each other, wanted to get a little bit of performance from my 1.4 OHC. It would be best if I could get something out below. What would be the best measures for this? Maybe let your head plan a little bit? Does a fan curvature also bring out below what? Achso 280er Nocke and Gr.A ab Kat are already installed. I would be grateful for many suggestions.