Julian,
I suspect it is your pipes. They are probably the older JHA design, which really makes the bike fall flat on its face at 11k rpm. Peak on those is in the mid-50's, provided the rest of the bike is in top shape.

Or your jetting may be a tad rich, killing the top-end.

Your port job will not net much at peak. The exhaust port timing was not advanced (raising of the port), but the blow-down timing was increased. You should notice the most increase in the 7-8k rpm range, and a tad more everywhere else. Basically, the same powerband you had previously, but beefed up everywhere and more noticable in the low-end of the "hit".

Also, I noticed something about the Daytona filters. They are dual-layer with a paper-thin layer of somewhat restrictive adhesive plastic in between (looked like a sheet of plastic with alot of holes). I was able to successfully peel the layers of mine apart and peel off the plastic layer. I then took some standard sewing thread and sewed the outer edges of the two layers back together. I can remove my entire airbox and notice no difference in power at all, just alot more noise.

Best way to clean the exhausts is to cook them. Red-hot with a torch, or run them through the "cleaning" cycle of an old oven that is no longer used to cook food.
_________________
Paul Herr
'88 FZR4/GSXR/YZF Frankenbike
MY BIKE PICS