hi grant this is the old man adrian not my son rich when i took the car to msd for a set up i spoke to stu about the top speed with the glebe gearbox he said on the live map they could not test the top speed although the fast ford feature said it started to tail of at 175 .in todays world grant you can get jailed for over 150 i think its better for mid range power.i am now thinking of having a new uprated rear beam for safety sake which shows are you going to this year we can meet up and have a chat cheers adrian