We just performed a HGP on our 1993 vintage 2055F Frame 7EA with steam injection (ratio set at 1.4) and Mark V controls in combined cycle. Coming out of the outage the machine is roughly 1.5MW down on power compared to its pre-outage operation yet it is consuming roughly 10% more gas. CPD and CPT are nearly the same, exhaust temps have risen 3F at 90MW. We have compared the fuel gas flow signal in the Mark V to our site utility meters and they are with 1% of each other. We have walked the entire site several times trying to identify gas leaks between the flow meter and the GT and haven't found anything. With this much extra gas going to the machine we should be overfiring and seeing a large increase in power yet we are actually down on MW's. During the outage we installed new GE fuel nozzles, 3rd stage buckets, first stage nozzle and combustion liners. The rest of the items were overhauled/new by a third party (LONG story...). The biggest part change was that the transition pieces we removed did not have the extra window pane cooling holes yet the new ones we installed did. Also wheelspace temps have barely changed and if anything are slightly lower. Any help would be greatly appreciated.