If someone from titleist Can chime in. I did some searches but could not come up with any answers. 

1.  I just received my 716 ap1 irons. With 85 tini graphite shafts. Are they still D1? You don't say what length, flex, grip, etc. but with std length, grip, grip size and stiff flex, the swingweight would be D2 +/-1

2.  I decided on playing 915hd hybrids. I have a 23.5 and installed a shaft 1/2 inch shorter. I think to get back to the original swingweight I would have to install the black 14 weight. Is that correct? Yes.  And what would the swingweight be of the hybrid? It depends on the shaft, the weight, flex, grip and grip size. 

3.  Is it better to have a heavier swingweight in my hybrids? If your tempo is quick or you are quick from the top, it might help you with timing. Or is that personal preference? Yes

4.  I played years with 60G shaft in my 913 and 915 driver. I recently switched to a heavier shaft 70G same length. Will that affect the swingweight of the driver? It depends

5.  Last question, does the 816h2 have more or less offset than the 915hd? Is there any significant technology advancement in the 816H that I should consider an upgrade?  Both the 915's and the 816's are really good hybrids.  The 816 has a relieved leading edge and relieved edges on the Active Recoil Channel to help it go through the turf smoothly.  The 816 H1 will launch slightly higher and is more forgiving than 915H.  We are offering more lofts to better fit players looking to improve their distance gapping and have changed the Surefit adaptor to allow for more adjustability.  ie:  up to 2° upright, 2° more loft vs 1.5° and 1° flatter, 1° less loft vs .75°. 

Thanks.