When filling a tire with my trunk inflater my rear goes up several inches and WillWren
asked me to post this subject here and link the post where it was brought to his attention and discussed. He says its the air system selecter valve at fault.
Also raised in the post is a dicussion about raising the rear intentionally to put more weight on launch and please put comments for that technique on this linked page.
If you have same problem as I, please post here and I would appreciate any info about problem you might have. Thanx John