No inspection in Michigan...

 

What you could do to secure a replacement ABS headliner in loose spots
is to use a few aftermarket trim screws with washers. These are the same
trim scew/washer combos that would be used in door panels.
They can be found in the HELP/Dorman part selection area of your local parts
house.

I have used them in a few ABS headliner replacements.

 

actually it was NOT done wrong, I put it up the way the previous headliner was in. the stock headliner had 2 clips that held the front up in place. but this being ABS plastic there is nowhere to mount the same clips. also was not done "hastily" I let it settle for a week to get the shape right before I put it in. but the 90* days made it warp and sag again. the only place to hold it up are the visor holes, dome light and seat belt covers, which clearly don't cut it. if you read my earlier posts I say that im working on some kind of clips to hold it up better.
not trying to start an argument but this is how it looks when installed the same way as the stock one (-) the 2 clips up front.

 

Getting ready to install mine just waiting to buy black seat belts off ebay

 

for you guys with the front sag issue. test fit the board in the car and make notes where it needs to be. take the clips from the old headliner, insert the clips where they normally should go and put some F-26 on the end of the clips and then insert the board back into the car.

the F-26 on the clips WILL NOT let go of the board once its cured. I have used this stuff to fix everything and its cheap and can be had at home depot or any hardware store.

this will allow the board to install and be held up like factory.