Trying to squeeze extra power from an n/a engine is always a tough one. You would be better starting with the handling side of things.
Decent rubber(depending on what you already have) will let you hold more of that speed you've worked up. Anti roll bars, drop links, coilovers. All will help to stiffen up the ride and reduce body roll again helping the car stay balanced and more able to hold its speed before letting go.
If you did want to go for power avoid getting a big diameter exhaust. The n/a needs back pressure the hold a good torque figure.
Aside from that, stick it in a pot ready for a turbo model [emoji5]