My diamante either bottoms out or hits the wheel well on turns.
Was looking to stop that and wondering what you guys know about this and hot to approach. Would it involve a much tighter suspension?

Couple of things might help
how many kms has the car done?
When you push down on the car is the suspension soft and bouncy?
Do the wheels hit the wheel arch when you turn it lock to lock stationary?
Do both wheels hit or just one? If one, which one?
Where abouts is it hitting the wheel arches (top, sides, front/back?) Can you provide a photo?

Most likely I'd say your struts have worn out with age.

Quick way to check your suspension, push down above wheel and immediately release, it should bounce up higher and settle down to its normal ride height. If it keeps bouncing you have a problem.