Might not be the fastest, but I was on a work trip with a bunch of coworkers, and one of the vans started leaking from the water pump. They called around, the best any shop could do was to take it in that Friday, when we were due to drive 8 hours back to Texas, and it was going to be $500 or something. After a couple of beers, I told them I had changed water pumps in 20 minutes before at home on my suburbans, and that the van shouldn't be that different (all LS stuff, BTW). They gave me grief about it, but I stuck to my guns that even being a van, 30 minutes tops. The next day, we got a new water pump, thermostat, coolant, etc., we got back to the hotel, all had a couple beers, then I went out and started the job. 28 minutes later, one of the guys came out to poke fun that I wasn't done yet, and found me finishing burping the system.