When I replaced ours, I noticed no significant difference - despite a home-brew testing apparatus I used that seemed to indicate some had a faulty spray pattern. Much, much later, we did have a problem (running on 3 cyl) that I narrowed down to one of the new injectors haveing failed - probably clogged. I still had the old ones, so it made that diagnosis much easier, and it's still running fine a year later with one old injector.

Since the injectors a relatively cheap for this model (here, at least), it pays to have a couple spares on hand.

Steve

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'91 MB 190E 2.3
'08 RAV4 Ltd 3.5
'83 Lazy Daze m'home 5.7