Yep, I agree with Eric, it could be done on the car I think. However, taking the pump off is actually trivial and then you can clean up things better on the work bench. Pulling the air box is 30 seconds, then it's only 1 wire plug, 2 bolts and a short hose and the pump is in your hand. My bearing had failed (disintegrated actually is a better term) so I wanted to inspect things closer and clean up the shaft etc. Eitherway would be fine though. Putting it back on was literally less than a 5 min job. I would estimate 10-15 minutes total for the actual pump removal and re-installation so it's not worth fretting about if you have any reservations about how difficult of a repair it is.