The changes id make are as follows:
1) Make the Raffles Blvd straight longer and go around the War Memorial like in the original track layout plan:
http://www.grandprix.com/ns/ns19001.html
2) Make turn 10 a more sweeping corner, but make it tight corner, but there is another alternative, take a right half way along the Padang and go around the courthouse and then blast along to the fullerton bridge.
3) the other change is that the stadium section exit should be a blast along to the final corner, but id like to see the exit go down the current escape road, and down to where Glock went off in FP3 today for a sharp hairpin. Makes it mickey mouse to a point, but safe for a blast around the last corner.
4) Last corner needs to be made more sweeping with a better pit entry thats wider and better than the present one. The final corner here should be a 200kph 5th gear balls the the wall commitment corner that will give the lap time if you ask it to and if you don't commit you will loose time. Im thinking something like Copse here would be freaking brilliant.