Try using a 303 and a single oscillator saw wave over the top. Its actually quite simle. Overdrive distortion helps also.

As for the second trip, you can try and get it from the Scot Project mix, I just had a listen then, there is a bit in the beginning of the song where it skips a beat and plays the bass. Otherwise, the original mix, there is the intro, then the beginning of the song, then the first breakdown. At the begining of the first breakdown, the bassline fades away by itself.

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