For some time now, I have wanted to reroute the cables on my 2012 Cervelo P2 to make it more similar to the routing on a 2015 Cervelo P2 (See below).
Unfortunately this requires taking a power drill to the frame to create the holes through which to route the cables.
The benefits of this modification (minor aesthetic improvement, a nano watt saved at 30mph, sense of achievement? clutching at straws...) didn't outweigh the risks for me (voiding warranty, drilling the holes wrong, cracking the frame, weakening the frame) and so I didn't ever take the plunge.
Then a few weeks ago a friend of mine (Ryan Davies) who happens to have the exact same frame, sent me a photo of his, post-modification, together with the offer of some spare parts needed to do the modification (mainly Jagwire bits, see images). This planted the seed in my mind, which quickly developed into it being an essential modification without which my bike would be virtually un-rideable. I started gathering all the necessary parts to get the ball rolling.
The method I followed is described on TriRigs YouTube channel here. I took some photos as I went along which can be seen below. Everything went very smoothly, and although I haven't empirically tested the frame and confirmed it isn't going to snap, I have every confidence the structural integrity hasn't been compromised. Time will tell...