Finally got the GTI back together this weekend! Aside form the cleaning, complete list of new parts is - intake manifold, fuel injectors, water pump, PCV valve, diverter valve, fuel filter, ECS clutch bleeder block and Diesel Geek short shifter. The intake manifold was the only thing that had actually failed, the rest is just maintenance or parts with known issues that I figured I'd replace proactively.
Was less hassle putting it back together than I expected, partly because I had the right tools, but mostly because I now knew how everything fits together. I wouldn't hesitate to do it again, and I'm sure I could bang through it in a day. Will definitely not be doing the chemical scrub on the valves again, though - I don't know how many brain cells the fumes cost me, but it's more than I can spare.
I'll buy the walnut shell blaster next time.
With that amount of carbon buildup at 143k km, I figure I should do it again in 100k km, or maybe even 75k. Haven't had a chance to drive it much, but definitely seems smoother and more eager to rev, and the little bit of part-throttle hesitation at certain rpms seems to be gone. Will need to do a proper test drive to be sure, though.
So far, the Diesel Geek shifter is a disappointment: shifts are certainly shorter (meh), but the notchyness that I disliked about the stock shifter is completely unchanged. They say it takes some time to break-in, but I'm skeptical. Guess we'll see.
I heard a fun little whoosh from the new diverter valve that I don't remember hearing from the old one. Old one was in surprisingly fine condition when I took it out, but the new one is a revised part and supposed to hold boost a bit better. Figured it was a cheap replacement, so why not.
Haven't totalled up the cost, but with all the stupid special tools I bought and screwing around with trips to the city for parts, I probably didn't save a ton of money. And of course, the shop wouldn't have taken two weeks, either (or was it three?) Car still needs a new timing chain tensioner and I'll replace the timing chain at the same time, just because. I'd thought about doing that myself, but will definitely be taking it to the shop for that one! Can't spare another three weeks without the car if/when I screw it up!