They have a slightly larger rolling radius which means it will raise the front end slightly. I used 70's on my 05 636 and never bothered touching the front or rear ride heights. If you are trying to cut a lap record, I could understand it, but at the pace we road riders run even on a track day it will never worry you. It was good enough for 1'46"s around the Island and 54's at Broadford so it can't be too bad!
Mind you, if it's a track day tyre you want, i highly recommend the Bridgerock 002 race tyres and the Metzler Rennsports/Racetechs are both good too. The Super Corsa's are ok, but I find they scallop out quickly. Whereas the metzlers give the same grip with better wear, and the 002's just stick like nothing else!! (ezpecially the fronts!!!)