I think the tunnel might be the wrong place for the barrel roll personally. After that plunge from the cliff, I think speeds in the tunnel will be to forceful and put to much stress on the track and riders. Some strobe light action would be awesome in there! I think the best place for the barrel roll, (well, at least the most awesome) is after the HUGE fan curve off the quarry, when you go back up where the trim brakes used to be before the boring helix, or like a combo barrel roll- div element right before you plunge into the tunnel. I think that would be cool and speeds would be just about right in my opinion. Also if the barrel roll is elevated, perhaps AFTER the tunnel near the station, so like a station barrel roll fly by.