Well my wife thinks her 02 Tahoe (5.3L flex) should have more power. I think it runs fine but don't know when the plugs and wire set were changed last so I said okay.

got a new set of wires ( thought it was great all eight wires are the same!!!) and installed Bosche Platinum +2. it ran terrible got a service engine soon and a p0300 code also. kept reseating the wires thinking I was getting spark leak. Finally replaced the plugs with Bosche Platinum +4, runs as good as ever. Not sure what was wrong with the first set of plugs maybe the electrodes were bent too close. thought I would just share.

FYI I have used the Platinum+4 in my ford ranger and really like them.

 

Have seen lots of trouble with Bosch plugs in these engines.
I recommend either the OEM AC Delco's or NGK's Iridium or IX Iridium plugs in your 5.3L