You may also need to consider using high agility craft for the fast speed classes such as phantom. You may want to get to grips with Feisar and its 100% handling for this can greatly help your lines around some of the tight corners at high speed. I say you may want use Feisar on rapier or phantom class for Sebenco. But once you become comfortable with the track and its lines swap back to Harimau for the better speed.

Never let go of the throttle, it kills your speed very fast, especially in conjunction with the use of airbrakes. Let go of the throttle and the AI will zoom past you. Just slam hard on your airbrakes but not for to long either to conserve speed. The only time you may need to let up on the throttle is Chengou projects left hairpin on phantom class.

That's all I can say without repeating Yeldars advice, but there's some of my tips if it helps