How to get a 500+ hp for M3 Convertible?

[Yeouyee Fang]

How to get a 400+ hp for M3 Convertible?

My M3 convertible with AC and Hamman tuning produces only 391 hp.
Is it possible to get 400+ hp without installing superchargers.

 

[MrElussive]

What did they do to the M3? There is a lot you can do, but without forced induction, you can't expect any ridiculous gains without SERIOUS engine modifications.