Hi Andy, As Mark D says, I competed at Curborough in May 2013 in an identical spec car to you (2009 academy car with A539 tyres, open diff and sealed academy engine). I went with a bunch of sprinters earlier that year to Northampton Motorsport for a rolling road session and my car came out at 118bhp which was the lowest of all class 1 and would explain your lower terminal speeds and if you look at the class 1 results for Curborough in May 2013 you will see very similar terminal speeds for me compared to you: https://www.lotus7.club/sites/default/files/images/users/11872/Curborough/Curborough%201%202013.pdf My fastest time that day was a 64.94s which was 0.5 seconds behind Robert Jacobs who was using an LSD and had already upgraded to the tracksport package. So the obvious upgrade path for you is LSD/tracksport. However, going back to your queries, I completely agree with Richard. I reckon it is 50/50 between upgrades and driver. You can spend fortunes on upgrades but that may only get you half way there - some advice/coaching and seat time in the car will help you with the other 50%. Feel free to message me directly if you would like any further advice. Mark