not quite, as i told you the cam timing was due to the TDC marking on the cams being out several degrees
I have read however that some belts do stretch, however this is only during acceleration and only by the very smallest margin - once the belt is running the cams on a standard or decelerating speed they hold their shape - spoke to several mechanics about this and they agreed it was all a theory that whilst true, didn't make any bearing upon the timing of the engine as a whole
-D
Edit - to add to petes post, why bother porting it at all? the gains are negligible and not worth it unless you're chasing that extra 1/10th a second around a track - waste of money on a streetcar but if u got the coin to spend a couple g's to get 5 extra kw then cool