No matter what I do I can't get the Normal over the line any quicker than 229km/h (may have done 230 once) and the Tuned 249. Surprisingly it doesn't seem to matter how well I take the penultimate corner as long as it's not stuffed up completely. What's your highest speed over the line? Given it's the longest full-throttle section the last two corners should be by far the most important.