Yeah, definitely strong, I've got them standing here right now, but I wouldn't say extremely strong compared to other Sativa strains +70-100%.
Unfortunately, I reacted a bit too late, but you can really influence the height during the stretch with light intensity. If you get a bit closer and give more power, it pushes the plants down a bit.
It's also important: With 12/12, always give at least 33% more light output than with 18/6, otherwise they'll get less light in the flowering stage than they did during the veg phase.