If you want speed there's 2 ways :
1) more power
2) better aero
3) do both.
4) Buy a light airplane
Improve the aerodynamics, Bonneville style : belly pan with rear diffusor ; plain wheel covers; nose job; agressive airdam; you'd probably be better off replacing the rear spoiler with the stock version on the Mazda 3 and then extend that aft and down.
Increase end gearing or at least top gearing so it can actually do 200+ mph in top gear without hitting the rev-limiter.
It's possibly electronically limited in top speed as well ?