The spring seats are at an angle anyway.
The twang you hear is the spring uncoiling, thuis is due to the bearings in the top mount seizing, not uncommon at all, I think the last time I bough bearings it was about £8 each.
Say you turn to the right, the spring bottom moves due to being located in the strut body, but the top stays where it is, so the spring is now tensioned that way, so when the tension overcomes the sticky top bearing it twangs back.
You would do wel to have your tracking at least checked when you have done mods like this.
tabetha