Hi, I have a 2010 softail, 16" apes, doing 140k's it's fine, but go to 150-160 and it gets a real bad front end wobble, Go any higher and it's a death trap. A mate took it for a ride, he weights about 160-170 kg's, he had bike flat out and no wobble. I am 115kgs. would changing to a heavier spring rate in the front end help, or are there any other things I can do to stop it or at least resduce this. Want to keep apes, love them. cheers for any suggestions.

cheers, food for thought.

Loose headstem bearings?

And tyre pressures. They will add to the wobble, especially the rear.

If you have air going up one Jean leg at high speed, that might cause a problem as your pulling the bike over to one side.
Be care for that, otherwise it could be any of the above.