Does anyone know of a really good time compress algorithm to preserve pitch? I might just write my own in MATLAB, but if something is out there...

We did scratch tracks (pre-demo) for a killer song that is only piano and vocals and it was at 108 bpm. It turned out great, but was done on a garbage keyboard.

When we went to my church to record on their grand piano, we did not use a click track and it sounded fine at the time (turned out to be at about 103 bpm). Now, when I sing to it, I am running out of breath and it's apparent that it's too slow.

The thing is, I've got 3 mics (separate tracks) that I need to time compress from 103 bpm to 108 bpm. Don't most algorithms (I use Nuendo) shift timing around if they try to preserve the tonal characteristics? I'd imagine the algorithm would not preserve timing amongst different tracks. Not to mention it doesn't sound very good. We might just go back to the church and re-track, but you know how it is, lugging all your gear over there when when there's an album deadline... not fun. ok, well yeah, it actually is sort of fun, but that's not what I meant...