The insulation under the hood was for sound deadening, not for heat issues.. You wont damage the paint by keeping it off. The biggest issue is trying to get all the glue off, you have to use "aircraft stripper" or something similar. There are some very good vendors [like Pelican] that sell 928 parts. I would buy the insulation from them over Ebay. It's usally cheaper and you have tech support to fall back on:
1) Pelican
2)
www.928intl.com
3)
www.devek.net
4)
www.928gt.com
Also, lots of info on "how-to's" for the 928 [and every other porsche] by going to
www.rennlist.com and looking at the web forums. They are similar to this one but have more users/info. I plan on using both the Pelican and Renllist forums.
"what worked for me may have been [likely] due to complete blind luck, your mileage may vary"