$500 is a great deal. I would have done in a heart beat for that. Based on past experience you want the shop that has done the most of these installations with good feedback. I've seen some not very good installations where there were creases, the latches didn't line up perfectly, the top started going up or coming down all weird, etc.
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The shop that quoted $500.00 labor likes the Robbins tops. He has followed in his fathers footsteps. A top knotch installer and businessman.
I was not sure about Robbins tops. So I have been waiting.
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2002 Boxster S Polar Silver Metallic, Hard Top
2016 4Runner TEP