Gravity's Rainbow and Trainspotting

I just realized that the incredibly visceral scene in Trainspotting, where Ewan MacGreggor's character goes down the toilet to chase after the suppositories he's just taken, is basically a total ripoff of the scene in Pynchon's Gravity's Rainbow, where Tyrone Slothrop goes down the toilet to get the harmonica he's dropped down it in his inebriated state.
Aside from this shit-surfing episode I'm finding Pynchon's magnum opus to be pretty difficult to get through. Luckily I only have like 600 more pages to go.