Homes were the same model and build date. I would have loved to have gotten a customer to buy window "X" and then swap them out for window "Y" but it didn't seem practical.
No other air sealing was done as part of the process.
Previous windows where double pane wood with compression, vinyl jambliners. Not in terrible shape but far from great.
I only had baseline data on the home that we replaced the windows on and not on the home that got window "X". The baseline was 3,800 cfm at 50 Pascals. When we were done changing the 20 double hungs (medium sized 32 by 62 and a few larger) the blower door number was just under 3,000 cfm if memory serves me correct. That got us right into the upper part of the MVR and the customer decided not to do any additional weatherization at that point.
The other home was not our customer but they asked that we take a look and inspect the windows for proper installation because of persistent drafts.
Windows were installed properly (level and square) and did not appear to leak between the frame and home. They were not foamed in place but the gaps were small and windows were measured tight. I did not observe any air infiltration in that location on the IR.
The blower door number was just over the baseline of the previous home at about 3,900 cfm. The customer was complaining of drafts at the meeting rail and along the jambs.
We installed chimney blocks and weatherstripping corner tabs on all the windows for the client and it did drop the number a decent bit to about 3,700. There was still a good bit of infiltration noted via IR camera but that can be a bit misleading as you and I both know.
Feel free to email me offline and I can disclose the brands. I don't think that it would be right mentioning in an open forum and especially since I didn't do the install or have the baseline data.