Hello All,
I will be having a new windshield installed and will attempt to install a new main targa seal as well. I was planning to have the windshield replaced first, but a friend suggested that I install the main targa seal first and get the targa top on the car prior to having the windshield installed to properly support the A-pillars and top connecting structure. My friend thinks this will make for a better windshield installation.
Any thoughts?

Kind of... Or you could just leave the old seal in with the top on.
After windshield is replaced, then you can change Targa seal.
Matt

Are the A pillars moving? If so there is other work that needs to be done before the windshield.

The A pillars are not moving and I should have added that I just had the windshield frame and cowl painted so there is no main targa seal on the car.

Your choice on what you do first. The two installs aren’t related

The A pillars flex a good bit on our cars. That's one reason why we don't generally recommend using urethane windshield adhesive, but the older butyl adhesive. The butyl has more give, and won't as easily crack the windshield when the A pillar flexes.

I can see that you might not want to have the top off when you install the windshield due to that.

--DD